Worcester Water Filtration Plant - Executive Summary
The City of Worcester Department of Public Works has developed a unified accidental release prevention program at its Worcester Water Filtration Plant (WWFP). The plan covers all aspects of the program 2 requirements under the United States Environmental Protection Agency (USEPA) 40 CMR 68. The DPW has documented a Risk Management Plan (RMP) for hazard identification, prevention and emergency response. this plan is coordinated with the regional Hazmat team, Local Emergency Planning Commissions of the City of Worcester and the Town of Holden and the Fire departments of both municipalities. Chlorine leak simulation drills are conducted yearly to coordinate the WWFP facility Emergency Response Plan into the City of Worcester's "Integrated Hazardous Material Incident Response Plan". This RMP has been electronically submitted to the USEPA. |
The WWFP has been providing the City of Worcester with quality drinking water since its opening on 1/9/97. The WWFP is located at 71 Ston
ehouse Hill Road in the Town of Holden on the shores of Holden Reservoir #2. Chlorine gas is used at the WWFP for final disinfection of the drinking water under the Federal Safe Drinking Water Act. The chlorination process includes a chlorinator room, scale room and chlorine storage room. The maximum storage of chlorine at the facility is 30,000 pounds. Chlorine is received in one ton cylinders containing liquid chlorine. Only chorine gas is released from the cylinders. Chorine gas is then mixed with water and is injected at a dose of approximately 2.5 parts per million. The facility is manned 24 hours a day, seven days a week by state certified drinking water operators. The chorine process is inspected daily and chlorine leaks can be detected instantaneously with the use of remote chlorine leak detectors within the WWFP. The alarm system alerts operators on duty both visually and audibly in the facility. The chlorine leak alarm is automatically sent out to the Town of Holden a
nd the City of Worcester emergency dispatch centers. The Fire Departments of both municipalities will respond to a chlorine emergency. The RMP coordinates the proper response from the operator in charge, the Fire Departments and LEPC's of both municipalities and the regional Hazmat team located in the City of Worcester. In the event of a chlorine leak the operators on duty are the first responders. The regional Hazmat team is the primary responder due to their training and available equipment. In the event of a fire the Worcester Fire Department is the primary responder because the Tatnuck Square Fire Station is the closest station to the facility. The two municipalities developed a mutual aid agreement before the completion of the treatment plant.
The offsite consequence analysis of the RMP includes the "worst case release" and the more realistic "alternative release". The "worst case release " is defined by the USEPA as the maximum quantity in the largest vessel releas
e in 10 minutes due to an unspecifed failure. The USEPA model, RMPComp, was used to determine the distance to a safe endpoint. The affected area reported using this model is very likely an overestimate of the affected area because the model uses weather conditions not representative of the area and does not take into account wind direction or topography. This scenario also dictates a catastrophic failure and complete release of an entire one ton cylinder in 10 minutes, which is highly unlikely. The maximum distance to a safe endpoint is 0.9 miles from the chlorine storage area. This would affect less than 300 people and only one public receptor. The public receptor that would be affected is a seasonal campground located in the Town of Holden. There are three environmental receptors in the affected area. Cascade Park is located between Mower Street and Cataract Street and is a passive recreation area consisting of hiking trails with no associated playgrounds area. The municipa
l Reservoir system of Holden Reservoir #1 and #2 are environmental receptors. No public recreation is allowed on these reservoir so there would be no public impact. The third environmental receptor is Cook's Pond. About a third of cook's Pond is in the affected area. Cook's pond is operated by a private lake association, which does allow recreation to members.
A more realistic event is the "alternative release". This event is an accidental breakage or failure of a flexible chlorine line under pressure. The maximum flow from this event would be through a 5/16" chlorine valve opening. This flow calculates to be 10 pounds per minute according to the Chlorine Institute. The chorine valve is designed using Chlorine Institute specifications. Assuming the leak can not be repaired, the entire maximum release would be 6000 pounds, which is the volume of three chorine cylinders that are hooked up to the same chlorine header. Therefore the release time would be 600 minutes. Thi
s release time would more than likely be reduced to less than 200 minutes by the actions of the regional Hazmat team. Even if the leak could not be repaired, the affected area would be 0.1 miles from the chlorine storage area. No residents or public receptors are located in this area.
The DPW prevention program includes the following key elements to prevent a chlorine leak from the WWFP. Operators at the WWFP are trained to prevent chlorine gas releases by understanding the associated chlorination equipment and the chlorine leak detectors. The chlorine leak detectors are tested once per month to insure that they will operate correctly in the event of an actual chlorine leak. The chlorine rooms are inspected daily and information logged on the operting parameters of the system. The operators are trained and competant in the use of Self-Contained-Breathing-Apparatus (SCBA) and have the knowledge of the chemical principals of chlorine. The operators work in pairs using SCBA'
s whenever chlorine cylinders are changed or a shipment of chlorine cylinders are received by the chemical supplier. These Standard Operating Procedures (SOP's) along with preventative maintenance performed on the chorine equipment greatly reduce the possibility of an accidental chlorine gas release.
There have been no chorine gas leaks in the operation of the treatment plant since the treatment planted opened on 1/9/97.
The facility has initiated a hazard review of the equipment and response program in 1999. The program will be reviewed annually by the DPW and will be audited within three years of the initial submittal. The response program is coordinated with the Worcester DPW, Local LEPC's of the Town of Holden and the City of Worcester, the Fire Departments of both municipalities and the regional Hazmat team. The system includes a response decision tree and notification plan. Emergency response drills are conducted annually with a review to evaluate the effectivene
ss of the plan.