Cliff Road Water Treatment Facility - Executive Summary |
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The City of Eagan has prepared a Risk Management Plan (RMP) for the Water Treatment Facility located at 1395 Cliff Road; Eagan, MN 55122. The purpose of this plan is to help prevent or minimize risk of exposure to chlorine gas for both employees of the facility and also the surrounding community. I. FACILITY DESCRIPTION The Cliff Road Water Treatment Plant treats an average of 3 million gallons of drinking water per day. The facility uses approximately 50 pounds per day of chlorine to disinfect the water system. During normal operations, the facility may have up to 8,000 pounds of chlorine stored at the site. The chlorine is stored in 2,000 pound containers. The facility is required to create a Risk Management Plan in compliance with Environmental Protection Agency Regulation 40 CFR 68. The reason for this is the facility maintains more than 2,500 pounds of chlorine on site at any given time. Creation of the RMP also provides compliance with the Process Safety Management (PSM) requirement in OSHA Regulation 29 CFR 1910.119. II. SAFETY CONSIDERATIONS The Cliff Road Water Treatment Plant has been safely treating the community's drinking water since 1991. In that time, no significant chlorine releases have occurred. The feed system operates on a vacuum principle with automatic shut-off if the vacuum is interrupted. This minimizes the risk of a major release due to damage of the chlorine piping system. The worst case and alternative release scenarios used to prepare this report assume all automatic shut-offs have failed. This facility is also equipped with a scrubber. In the case of a major leak (example of a major release would be the rupture of a 2,000 pound chlorine container), the scrubber is capable of removing 2,000 pounds of chlorine gas from the air prior to being vented to the atmosphere. This is the primary line of defense in protecting the surrounding community from the hazards associated with a major chlorine release. All release scenario s used in this plan assume the scrubber is not operating during the release. In reality, a major indoor chlorine release would not have any noticeable affect on the community because the scrubber would remove the chlorine from the air prior to release. The assumption of an inactive scrubber during a major release is considered a worst case scenario. The facility is also equipped with an emergency back-up generator capable of running the entire plant during a power outage. III. WORST CASE RELEASE SCENARIO The Risk Management Plan regulations require modeling the potential affects caused by the anticipated worst case chlorine release scenario. The worst case release scenario for the Cliff Road Water Treatment Plant is defined as: * Catastrophic failure of a 2,000 pound chlorine container due to corrosion, impact, etc. * 2,000 pound total chlorine release * 200 pounds/minute release * 10 minute duration * Atmospheric Stability Class F * Wind Speed = 1.5 meters per second * Te mperature of between 88 and 107 degrees Fahrenheit * Chlorine scrubber is not operating The influence radius of the worst case release is 2.63 miles according to EPA's Off-Site Consequence Analysis Guidance Reference Tables. The estimated population within the circle of influence is 38,000 based on Census numbers. There are several critical receptors within the influence circle including schools, residences, recreation areas, and major commercial/office areas. The Minnesota Zoo is also located within the influence circle. IV. ALTERNATIVE RELEASE SCENARIOS Alternative release scenarios more accurately reflect potential releases than the worst case scenario. Since alternative releases are more likely to occur, these scenarios are generally considered more useful for emergency planning. One possible scenario was considered for this facility. A. Alternative Release Scenario The alternative release scenario assumed the following conditions: * Tubing failure, bad connection or val ve failure resulting in release of chlorine gas through a 5/16" diameter opening * 317 pound total chlorine release * 10.5 pounds/minute release * 60 minute duration * Atmospheric Stability Class D * Wind Speed = 3.0 meters per second * Temperature of 77 degrees Fahrenheit * Chlorine scrubber is not operating The influence radius of this release scenario is 0.48 miles according to EPA's Off-Site Consequence Analysis Guidance Reference Tables. The estimated population within the circle of influence is 1,300 based on Census numbers. Critical receptors within the influence circle include residences and recreation areas. V. EMERGENCY RESPONSE PROGRAM Emergency response would be required in the rare occurrence of a major chlorine release. The Cliff Road Water Treatment Facility is included in the Eagan community emergency response plan. In the event of an emergency chlorine release, an employee of the facility would be responsible for calling the Eagan Fire Department. The fire department would assess the situation and determine if the St. Paul HAZMAT team needs to be notified. These people are trained in handling emergency situations dealing with hazardous materials. The fire department and/or the HAZMAT team would be responsible for mitigating the effects of a release and coordinating evacuation procedures if necessary. A training program has been established to insure all employees of the water treatment plant can identify an emergency situation and understand the procedure for notifying the proper authorities. As a part of this program, facility employees will annually meet with representatives of the fire department to discuss potential hazards. This will also allow the fire department to gain familiarity with the layout of the treatment plant and grounds. VI. IMPLEMENTATION OF THE RMP/PSM PROGRAM The facility has implemented written procedures in compliance with the RMP/PSM regulations to help minimize the risk of a chlorine release. The newly c reated RMP/PSM manual outlines training requirements, operating procedures, maintenance procedures, and defines responsible persons for implementing the different aspects of the plan. The RMP/PSM plan is a tool that will provide guidance for the facility in day to day operations thereby creating a safer and more effective work environment. |