Mill Service, Inc. - Executive Summary |
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Mill Service, Inc. (MSI) is committed to worker and public safety in the operation of our Yukon facility. This commitment to safety is demonstrated by the elements of our accident prevention program, which include operating procedures, personnel training programs, and engineering and administrative controls in our process. MSI utilizes a process safety management (PSM) program to ensure that our chlorine wastewater treatment system is operated in a safe manner. MSI operates a facility for treating liquids, dusts, sludges and contaminated soils. Treatment processes include neutralization of acid wastes and stabilization of metal-bearing wastes and contaminated soil. MSI operates a wastewater treatment plant that treats wastewater and leachate from plant operations. The wastewater treatment plant uses chlorine to treat the wastewater. The facility may store up to six one-ton containers of chlorine at any time. Full chlorine containers are stored in two wooden sheds called the c hlorine use sheds. Empty containers are stored in a third wooden shed. Chlorine used in treating wastewater is withdrawn in the gaseous state from an active container. The discharge from the container is controlled by a regulator mounted on the container valve. Because MSI's chlorine treatment system is subject to OSHA PSM standards, the system falls under Program 3 requirements according to EPA's Risk Management Program. MSI does not have any Program 1 or Program 2 processes at the Yukon facility. The worst-case release of chlorine at the facility would be a catastrophic release of 2,000 pounds of chlorine from a one-ton container over a 10-minute period. MSI uses numerous administrative and active mitigation systems to minimize the consequences of such a release; however, the extent of the release was calculated without taking credit for any mitigating factors. This is in accordance with EPA requirements in calculating the effects of a worst-case release. The estimated di stance to the toxic endpoint of 0.0087 mg/L is 2.2 miles, and a residential population of 4,400 would potentially be impacted. EPA's model, RMP*Comp, was used in estimating the distance to the toxic endpoint, and the US Census Bureau internet site was accessed to estimate the residential population. The alternative release scenario for chlorine is a failure between the regulator and cylinder valve, resulting in a leak of 37 pounds per minute from the one-half-inch diameter valve. It is estimated that the leak could continue for 60 minutes before being stopped. Although unlikely to occur, this release scenario is more likely to occur than the worst-case release scenario described above. This release would be minimized by MSI's mitigation systems, such as chlorine sensors and alarms, check valves, and operating procedures. The distance to the toxic endpoint for this scenario is 0.2 mile, which would impact a residential population of 12. The release rate and distance to the toxic endpoint were developed using EPA's Risk Management Program Guidance for Wastewater Treatment Plants and RMP*Comp, and the residential population was estimated from site knowledge. The wastewater treatment process at the facility that is regulated by the RMP is also regulated by OSHA's PSM standard. MSI's PSM program includes process safety information on the chlorine system. MSI conducted a process hazards analysis to identify hazards and ensure that adequate controls are in place to manage the hazards. Operations at the facility are conducted according to standard operating procedures, and employees are trained on the procedures. MSI ensures mechanical integrity of its chlorine treatment system by conducting routine inspections and promptly correcting identified deficiencies. MSI's chemical-specific release prevention programs include process control monitors to maintain the operating conditions of the chlorination system; a chlorine gas sensor connected to an alarm in the sto rage sheds; and check valves, gas regulator vents, and a float operated kill switch to minimize the impact of process upsets. MSI had no accidental releases of chlorine in the past five years that resulted in onsite or offsite injuries or deaths, onsite property damage, or offsite environmental damage. MSI maintains a written emergency action plan (EAP) that describes actions to be taken in response to a chlorine leak or a fire in the vicinity of the chlorine storage and use sheds. The EAP contains response procedures for employees and the manager on duty. MSI maintains a Chlorine Institute Emergency Kit "B" for responding to one-ton container emergencies. Spill response actions are coordinated with the Westmoreland County LEPC, and fire response actions are coordinated with the Yukon South Huntingdon Township Fire Department. Planned changes to improve safety at the facility include continued training of employees on the safe handling of chlorine. |