Howard Avenue Water Purification Plant - Executive Summary |
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Executive Summary Introduction Chemicals are widely used in industry, in the home, and in the environment and are an integral part of everyone's daily lives. They are transported on roads, water, and railways. The City of Milwaukee Howard Avenue Water Purification Plant (WPP) uses chemicals, too. The plant uses propane to heat plant buildings in the winter when the natural gas supply is curtailed by the gas company. This allows the plant to continue to provide safe drinking water under the most adverse winter weather conditions. Storing chemicals can be a hazard. We take our safety obligations in storing and using chemicals as seriously as we take providing our customers safe drinking water. The following document describes what could happen if there were to be an accident, the steps we take everyday to ensure that our plant operates safely, and what we do in the event of an emergency. Regulatory Background The USEPA's Clean Air Act Amendments of 1990 included provisions that r equire facilities that use certain substances to develop a formal plan to reduce the likelihood of an accidental release of the substances to the atmosphere and reduce the likelihood of serious harm to the public and the environment. Before these regulations were in place, the Howard Avenue WPP had already established many of the components of the plan. The requirements of this plan, commonly referred to as a Risk Management Plan (RMP), are detailed and codified in 40 CFR Part 68. The Howard Avenue WPP stores propane in quantities above the regulatory thresholds at which a RMP is required. Propane, which is also known as liquefied petroleum gas, is what is commonly used in homes and businesses in rural areas for heating, cooking, and other household and industrial purposes. The Howard Avenue WPP utilizes propane to heat buildings. Propane Process Safety Systems The Howard Avenue WPP stores propane in a 30,000-gallon horizontal tank. Propane is mixed with air and fed to the plant boile rs. Propane is very flammable and may be explosive. In addition, it is an irritant to the respiratory system, eyes and skin. Exposure through inhalation at high concentrations may cause asphyxiation. Contact with the skin and mucous membranes can cause burns similar to frostbite. To prevent accidental releases from occurring that may cause these injuries, the Howard Avenue WPP's propane system has been designed with several safety features. These safety features along with the Prevention Program described below greatly reduce the possibility of a significant release of propane from occurring. To date, the safety features in place have allowed the Howard Avenue WPP to achieve an excellent record in preventing accidents. No propane release causing a safety or health hazard has occurred since the system was installed in 1995. Safety features designed into the propane system help reduce or eliminate the consequences of an accident, much like seat belts reduce injuries in car accidents and anti-lock brakes help avoid car accidents. But, unfortunately accidents can occur. By being prepared for an accident, we can handle the situation in a way that protects those around us. At the Howard Avenue WPP we prepare for an accidental release by planning a course of action to address and handle the situation. The Emergency Response Program details appropriate courses of action to be taken in the event of a release and is designed to protect people inside as well as outside of the plant. The combination of design safety features and the Emergency Response Program greatly reduces the risk due to a potential accidental release for people inside and nearby the plant. Components of the RMP The RMP consists of three major parts. The first part is the Hazard Assessment. The Hazard Assessment is done to determine the effects that a release of a regulated substance could have on the public. The second part is a Prevention Program that consists of 7 elements designed to improve the system safety and decrease the likelihood of a release. The third part is the Emergency Response Program, which develops a plan for dealing with a release in the unlikely event that one would occur. Hazard Assessment A Hazard Assessment was performed to determine the effects a release would have on the public. For propane, the area of impact is determined by estimating the distance to the flammable endpoint. The flammable impact is the outside of the explosion shock wave (1-psi overpressure), along which broken glass and other similar structural damage may occur. In addition, an estimate of the population outside of the plant boundary that could be impacted was determined, and sensitive receptors such as hospitals, schools, and parks were identified. The Hazard Assessment considers two release scenarios-a "worst case" and an "alternative release." The Offsite Hazard Assessment for the Howard Avenue WPP was completed in March 1999. A summary of the assessment is provided below. Wors t-Case Scenario At the maximum fill level the propane tank contains approximately 94,000 pounds of propane. The worst-case scenario assumes that the entire tank of propane is catastrophically released at once, a flame or spark then ignites the propane, and it explodes. For an explosion to occur would require the correct mixture of propane and oxygen. These set of assumptions as well as others used to estimate the impact area, result in a set of conditions that are highly improbable. A computer program (RMP* Comp, Version 1.04) was used to estimate the flammable endpoint. The results from the RMP* Comp estimate that an instantaneous release and explosion of the entire contents of the propane tank at the Howard Avenue WPP would impact a distance of 0.4 miles from the propane tank. Alternative Scenario The alternative case scenario for the Howard Avenue WPP assumes that the pipe on the discharge end of the feed pump ruptures during tank filling. The propane release is assumed to be the qu antity released after the pump runs for 3 minutes after the pipe breaks and the quantity released from the fill line until the manual valves are closed. The released propane creates a vapor cloud which encounters an ignition source and explodes. The release quantity was calculated to be 39,525 pounds. The RMP* Comp output estimates the distance to a 1-psi overpressure is 0.2 miles. Population and Environmental Receptors Potentially Exposed to Accidental Releases The population affected by each accidental release was determined using Landview. III, a computer database program developed the U.S. Department of Commerce, Bureau of the Census. The data base program estimated populations of 1,600 and 360 for the worst-case and alternative case scenarios, respectively. Other potential receptors identified were public recreation areas within the worst-case scenario impact zone. Prevention Program The Prevention Program consists of 7 elements designed to improve the system safety and decrease t he likelihood of a release. Safety Information The RMP regulations require that information concerning process chemicals, technology, and equipment be compiled as part of a RMP program. Emergency response planners can use such information to develop training programs and procedures, or as a general resource. The information will be supplied to contractors who will work in the propane process area. All the required process safety information was compiled as required by the RMP regulations. The information meets and in many cases exceeds the minimum required by the regulations. Hazard Review A hazard review was conducted systematically to evaluate potential causes and consequences of accidental releases. This information will be used by Howard Avenue WPP staff to improve safety and reduce the consequences of accidental releases. The propane Hazard Review was conducted by CH2M HILL with the assistance of Howard Avenue WPP staff familiar with the process operation and maintenance and plan t management. The review was done using a "Checklist" method. Based on the results of the review, some changes in operating, maintenance, and other process safety management procedures that would improve the overall safety of the propane system were identified. The changes that most effectively help prevent an accidental release will be implemented. Operating Procedures Operating procedures for the propane system have been developed. Written operating procedures assure continuous, efficient, and safe operation of the facility. The goal of the operating procedures is to provide clear instructions to safely operate the process. Operating procedures are also used to train new employees and to provide refresher training for existing staff. The detailed operating procedures include startup and shutdown operating procedures. The procedures describe how the system should be operated in order to minimize the chances of an accidental release. The procedures also emphasize safety considerations during operation. Training An effective RMP training program can significantly reduce the number and severity of accidental release incidences. Employees involved in operating or maintaining the propane system receive training that includes applicable operating and maintenance procedures and an overview of the process. Training must emphasize safety and health hazards and safe work practices. Milwaukee Howard Avenue WPP staff received initial training following installation of the propane system in 1996. Refresher process operation training is provided annually. Maintenance An effective maintenance program is one of the primary lines of defense against a release. The maintenance program also addresses equipment testing and inspection, preventative maintenance schedules, and personnel training. The intent is to ensure that equipment used to process, store, or handle propane is properly maintained and installed to minimize the risk of releases. The Howard Avenue WPP uses plant maintena nce personnel to perform preventive and corrective maintenance on the propane system. All plant maintenance staff will be trained to properly and safely perform the maintenance. Preventive maintenance for the propane system is tracked by the plant's computerized maintenance management system (Eagle Protius). The maintenance management system is use to store equipment information, generate and prioritize work orders, schedule preventative maintenance (PM). Incident Investigation Each incident that resulted in or could reasonably have resulted in a catastrophic release of propane must be investigated. A process to identify the underlying causes of incidents and implement procedures for preventing similar events has been developed. To investigate an incident, an investigation team will be established. As part of the investigation, an incident report will be prepared to recommend system changes to prevent the incident from occurring in the future. The investigation team should ask questio ns such as what equipment failed or which behavior failed? As part of the incident review, staff actions that may have contributed to the incident will also be reviewed. A determination will be made as to whether it is necessary to institute additional training for the employees to prevent the incident from occurring in the future. The incident investigation report and any changes resulting from the report will be reviewed with all staff members who operate and maintain the applicable system. Compliance Audit The Howard Avenue WPP will complete a compliance audit for the RMP program plant at least once every 3 years. The primary goals of conducting a compliance audit are to verify compliance with RMP requirements and good process safety practices, identify process safety deficiencies and develop corrective actions, and increase safety awareness among plant staff. The compliance audit methodology is modeled after OSHA's guidelines for conducting regulatory PSM compliance audits: Compli ance Guidelines and Enforcement Procedures, OSHA Instruction CPL 2-2.45A (September 28, 1992). An auditor knowledgeable in the covered processes, RMP requirements, and audit techniques will conduct the audits. Based on the results of the audit, the plant will promptly determine an appropriate corrective action for each deficiency identified during the audit. Emergency Response Program The Emergency Response Program develops a plan for dealing with a release. EPA RMP regulation 40 CFR 68 Subpart E require that an Accidental Release Emergency Response Plan be prepared. The plan must be prepared in accordance with the provisions of another overlapping OSHA regulation-Employee Emergency Plans (29 CFR 1910.38(a)). The Emergency Planning and Response plan provides specific emergency response procedures for accidental releases of propane. As part of the emergency response procedures there are plans evacuating the plant and communicating local emergency response support agencies. In addition, critical plant operations are identified to insure that, if possible, the critical Howard Avenue WPP functions are kept operational. The Emergency Planning and Response plan also addresses plant site communication, emergency response equipment, first aid and medical treatment, medical surveillance and consultation, and emergency response drills. |