Clemson University Wastewater Treatment Plant - Executive Summary
EXECUTIVE SUMMARY FOR CLEMSON UNIVERSITY WASTEWATER TREATMENT PLANT |
ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES
The Clemson University's accidental release prevention and emergency response policies show that the Clemson University is strongly committed to employee, public and environmental safety and adheres to all applicable regulations. The comprehensive accidental release prevention program covers areas such as safety, hazard analysis, operating procedures, maintenance and employee training associated with the processes at the facility. The effective emergency response plan covers response procedures such as pre-emergency employee training, lines of authority, emergency recognition, evacuation routes and procedures and emergency medical treatment. It is the Clemson University's policy to implement appropriate measures to prevent possible releases of regulated substances.
STATIONARY SOURCE AND REGULATED SUBSTANCES HANDLED
The Clemson University Wastewater Tr
eatment Plant has one (1) regulated substance at the facility above the threshold quantity. The regulated substance is chlorine with a threshold quantity of 2,500 lb. Chlorine is used in the wastewater treatment process at the facility. Chlorine is handled in one ton cylinders and the maximum amount of chlorine handled is 4,000 pounds. The Clemson University is mandated to meet Program 3 requirements.
The offsite consequence analysis includes consideration of two chlorine release scenarios, identified as "worst case release" and "alternative scenario". The worst case release scenario is defined by EPA as a release of the largest storage vessel over a ten (10) minute period due to an unspecified failure. The alternative release is defined by EPA as a release that is more likely to occur than the worst case release. The Clemson University chose DEGADIS+ to perform the air dispersion consequence modeling due to the nature of the chemical and the release scenario
The worst case release scenario involves a catastrophic release from a one ton cylinder (2,000 lb.) of chlorine in a gaseous form over 10 minutes from an enclosed building. Since the chlorine is enclosed in a building, the release is mitigated and the release rate can be reduced by 45%. The mitigated worst case release rate would be 110 lb/min. The worst case release was analyzed at Class F atmospheric stability, 1.5 m/s wind speed, 100 F, 71% humidity and 0.03 m surface roughness for the maximum distance to the toxic endpoint of 0.0087 mg/L (3 ppm). The worst case release resulted in offsite impact.
The alternative release scenario for chlorine involves a partial valve failure on a one ton (2,000 lb.) cylinder of chlorine resulting in the release of gas through the 5/16" opening. The failure released the entire contents of chlorine in a gaseous form from an enclosed building. Since the chlorine is enclosed in a building, the release is mitigated and the release rate can be r
educed by 45%. The mitigated alternative release rate would be 6.3 lb/min. The alternative release scenario was analyzed at Class D atmospheric stability, 3.0 m/s wind speed, 60.4 F, 71% humidity and 0.03 m surface roughness for the maximum distance to the toxic endpoint of 0.0087 mg/L (3 ppm). The alternative release did go offsite, but did not result in any offsite impact.
The alternative release is much more likely to occur at the facility than the worst case release scenario. The worst case release is unrealistic because at that high of a release rate, the chlorine will most likely freeze over the hole in the container which will prohibit more chlorine gas from escaping. It is not appropriate to compare a 10 minute release to a one hour exposure time standard. The toxic endpoint concentration is based on a one hour exposure time, while the worst case release occurs over a ten minute period. Therefore, the ten minute release period is used as the averaging time instead of one
hour exposure time. Realistically, if a person can withstand a certain concentration over a one hour period with no health effects, they could withstand a higher concentration over a ten minute period. One solution would be to adjust the toxic endpoint value to correlate to the ten minute exposure during a worst case release instead of the one hour standard. However, there is no allowance in the RMP rule by the EPA to make this adjustment.
ACCIDENTAL RELEASE PREVENTION AND CHEMICAL SPECIFIC PREVENTION
The Clemson University has taken all the necessary steps to comply with the accidental release prevention requirements set out under 40 CFR part 68 of the EPA. The process is subject to the OSHA PSM standard under 29 CFR 1910.119 and is already in compliance. The following steps are key to the prevention program:
1. Detailed records of safety information describing the chemical hazards of chlorine, process technology, and process equipment.
2. Comprehensive process hazard analysis
are conducted to ensure that hazards are recognized and evaluated.
3. Operating procedures have been developed and implemented which describe tasks to be preformed, dates to be recorded, operating conditions to be maintained, emergency operating procedures and safety and health precautions to be taken.
4. Employee training program is in effect to ensure that the employees of the Clemson University Wastewater Treatment Plant are properly trained and aware of all safety practices, hazards, emergency procedures and maintenance procedures.
5. An on-going mechanical integrity program is in place to ensure safe process operation.
6. Incident investigation procedures are in place to ensure that all unplanned events affecting process safety are properly investigated in a timely manner to identify the causes of the incident and to implement corrective action.
FIVE-YEAR ACCIDENT HISTORY
The Clemson University Wastewater Treatment Plant has had an excellent record of preventing accidental relea
ses over the last five years. Due to the effective release prevention policies, there have been no accidental release during the last five years.
EMERGENCY RESPONSE PLAN
The Clemson University Wastewater Treatment Plant has a written emergency response plan to deal with accidental releases of chlorine and other hazardous materials, which has been coordinated with the local emergency response personnel. The plan includes all aspects of emergency response including adequate first aid and medical treatment, evacuations, and notification of local emergency response agencies and the public.
PLANNED CHANGES TO IMPROVED SAFETY
The last Process Safety Hazard Analysis was performed during the initial development of the Process Safety Management Plan in January 1999 and it resulted in one recommended change at that time. It has been recommended that the University install a wind sock near the chlorine building so they can determine wind direction in the event of a chlorine release. This
wind sock should be installed by April 1999.