Southerly Wastewater Treatment Plant - Executive Summary |
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The Southerly Wastewater Treatment Plant (WWTP) Chlorination/Dechlorination Facility utilizes more than a threshold quantity of chlorine (2,500 pounds) and sulfur dioxide (5,000 pounds) in their process. Therefore, this facility is required to submit a Risk Management Plan (RMP) as defined in 40 CFR Part 68.150 by June 21, 1999 (three years after publication of the final rule). Since public employees are covered under the state of Ohio's Public Employee Risk Reduction Program (PERRP), Southerly WWTP is subject to OSHA's PSM standard (29 CFR 1910) and is therefore subject to Program 3 requirements. USEPA's RMP rule requires that covered facilities prepare an executive summary. The following pages represent the executive summary, summarizing the items required as described in 68.155 (a) through (g). 68.155(a) Accidental Release and Emergency Response Policies Southerly WWTP has emergency procedures in place, as documented in the facility's Emergency Action Plan. This plan has proc edures for both onsite activities and coordination with offsite responders that must be followed in the event of a chlorine or sulfur dioxide leak. All personnel involved in handling chlorine or sulfur dioxide are trained on chlorine/sulfur dioxide safety and accident prevention. 68.155(b) Stationary Source and Substance Handled The stationary source subject to 40 CFR Part 68 is the Southerly Chlorination/Dechlorination Facility. Southerly WWTP is a 114 million gallon per day (MGD) design capacity advanced secondary wastewater treatment plant. Southerly's Chlorination/Dechlorination facility is divided into two separate rooms: the Storage Room and the Chlorination/Dechlorination Room. The storage room can hold up to eight banks of six one-ton containers. However, the maximum intended inventory is 15 one-ton containers of each chemical. The containers store either chlorine or sulfur dioxide as a pressurized liquid. The Chlorination/Dechlorination room has four scales that can ea ch hold one chlorine container and two scales that can each hold one sulfur dioxide container. There is a single one-ton container of chlorine on-line at all times with one container on stand-by for changeover when the contents of the on-line container are exhausted. The same practice applies for the sulfur dioxide, one container in use with one on standby. The chlorine and the sulfur dioxide are fed as a liquid into individual evaporators (one evaporator for each scale), where the chlorine or sulfur dioxide is converted to a gas, fed through a chlorinator or dechlorinator, and then pulled under a vacuum and injected into various process waters. Chlorination and dechlorination processes are only used for approximately 6 months from May 1 to November 1 each year. Chlorine and sulfur dioxide containers are delivered just before the start of the season, usually mid to late April, and any containers remaining at the end of the chlorination/dechlorination season are shipped back to the supplier as soon as possible. Therefore, these chemicals are on site for no more than seven months per year. Southerly WWTP is equipped with safety devices to prevent a release and decrease response time in the event of a chlorine or sulfur dioxide leak. Three chlorine leak detectors and three sulfur dioxide detectors are located throughout the Chlorination/Dechlorination Room. Three more chlorine leak detectors and three more sulfur dioxide detectors are located in the Storage area. Audible alarms automatically sound inside and outside the building when chlorine levels or sulfur dioxide levels reach one part per million (1 ppm). There is also one chlorine alarm in the basement of the chlorine/sulfur dioxide facility and one chlorine alarm in the basement of the chlorine contact tank basin. In addition, the chlorinators and sulfonators are vacuum fed. The vacuum condition causes air to be drawn into the unit when a leak occurs, rather than chlorine or sulfur dioxide gas escaping from the system. 68.155(c) Offsite Consequence Analysis The Southerly WWTP has chosen to use the US EPA Risk Management Program Guidance for Wastewater Treatment Plants (40 CFR Part 68), US EPA 550-B-98-010, revised March 1999, (WWTP Guidance), as a source to determine off-site consequences. This guidance specifically addresses the chemicals commonly found at WWTPs, such as sulfur dioxide and chlorine. The facility is required to complete at least one worst-case release scenario per USEPA 40 CFR Part 68.165(a)(2). Although Southerly WWTP has two covered toxic chemicals, the one worst case release scenario that represents all of the possibly effected environmental receptors is used as the worst case release scenario for the facility. The worst-case release scenarios were determined in accordance with the requirements provided in 40 CFR 68.22 and 40 CFR 68.25(b,c). The worst-case release scenario for sulfur dioxide has the largest distance to the toxic endpoint and encompasses a ll of the same environmental receptors that the worst-case release scenario for chlorine effects and more. Therefore, the worst-case release scenario reported for Southerly WWTP is the worst-case release of sulfur dioxide. This scenario is the release of 2,000 lbs (largest vessel) in 10 minutes and it does have offsite impacts. The facility is required to conduct a separate alternative release scenario for each chemical. The alternative release scenarios were evaluated in accordance with the guidelines provided in 40 CFR 68.22 and 40 CFR 68.28. The most likely release scenario is identified based on the results of the Process Hazard Analysis (PHA). However, if this scenario does not reach an endpoint offsite, 40 CFR 68.28 requires a different scenario be chosen that will potentially reach an endpoint offsite. At Southerly WWTP, the most likely release of sulfur dioxide identified in the PHA will not reach an endpoint offsite, using the release guidance in the USEPA RMP Guida nce for WWTPs. Therefore, Southerly WWTP is required to identify a less likely scenario that results in an endpoint offsite as their alternative release scenario for the RMP. The alternative release scenario for sulfur dioxide that results in offsite impacts is therefore a flashing liquid release through a 5/16 inch opening from a valve or hose failure. This scenario incorporates the passive mitigation of the building. The alternative release scenario for chlorine that results in offsite impacts is a flashing liquid release through a 3/16 inch opening from a leaking valve, hose, gasket, or pipe. This scenario incorporates the passive mitigation of the building. 68.155(d) Accidental Release Prevention Program The Southerly WWTP facility has a documented Prevention Program for the Chlorination and Dechlorination Systems that document release prevention measures. These prevention measures include elements such as Employee Participation, Process Safety Information, Process Hazard Analysis, Operating Procedures, Training, Contractors, Pre-startup Review, Mechanical Integrity, Hot Work Permits, Management of Change, Incident Investigation, and Compliance Audits. Southerly WWTP is equipped with safety devices to prevent a release and decrease response time in the event of a chlorine or sulfur dioxide leak. Three chlorine leak detectors and three sulfur dioxide detectors are located throughout the Chlorination/Dechlorination Room. Three more chlorine leak detectors and three more sulfur dioxide detectors are located in the Storage area. Audible alarms automatically sound inside and outside the building when chlorine levels or sulfur dioxide levels reach one part per million (1 ppm). There is also one chlorine alarm in the basement of the chlorine/sulfur dioxide facility and one chlorine alarm in the basement of the chlorine contact tank basin. In addition, the chlorinators and sulfonators are vacuum fed. The vacuum condition causes air to be drawn into the unit when a leak occurs, rather than chlorine or sulfur dioxide gas escaping from the system. 68.155(e) Five-Year Accident History The Southerly WWTP facility has had no accidental releases of chlorine or sulfur dioxide in the last five years that have resulted in on-site injuries or off-site injuries or other impacts. 68.155(f) Emergency Response Program The Southerly WWTP is a non-responding facility, as defined by OSHA and USEPA (29 CFR 1910.120 and 40 CFR part 311). Therefore the Southerly WWTP has developed an Emergency Action Plan to ensure employee safety instead of an Emergency Response Program, as allowed by 40 CFR 68.90(b). The Southerly WWTP facility Emergency Action Plan outlines actions required to respond to a chlorine or sulfur dioxide emergency and has coordinated this plan with the Hamilton Township Fire Department and the Franklin County Local Emergency Planning Committee (LEPC). Hamilton Township Fire Department personnel are the designated first responders, bu t in the event of a chlorine or sulfur dioxide emergency assistance from the Columbus Fire Department Hazardous Materials Unit will be required. Southerly WWTP employees are not designated responders to a chlorine or sulfur dioxide release. As specified in 40 CFR 68.90, Southerly WWTP's Emergency Action Plan meets the exception listed in 40 CFR 68.90(b) and therefore, the facility is not required to have the Emergency Response Program of 40 CFR 68.95. 68.155(g) Safety Improvements Recommendations for safety improvements were identified in the Process Hazard Analysis (PHA) which was completed per OSHA 29 CFR 1910.119(e) in November of 1998. Recommended improvements were identified in three main categories: Standard Operating Procedures, Maintenance, and Training. According to the Process Safety Management Plan, any safety improvements will be investigated concerning their impacts on other systems and/or procedures prior to implementation. Additional recommendations may be made up on review of any accidents, system modifications, and/or when the PHA is updated every five years. A program audit, conducted every 3 years can also produce recommendations of safety improvements or program revisions. |