Town of Webster Wastewater Treatment Plant - Executive Summary
The Town of Webster, Massachusetts owns and operates a Wastewater Treatment Plant (WWTP) within the Town limits. The Webster Sewer Department (Department) has developed a Risk Management (RM) Program for the control of catastrophic releases of extremely hazardous substances at the WWTP. The RM Program continues the Department's commitment to the protection of its neighbors and its employees and the control of the potential for such a release. |
The U. S. Environmental Protection Agency (EPA) issued the Chemical Accident Prevention rule (40 CFR 68) in June 1996. This rule requires any facility with a process that involves more than a threshold quantity (TQ) of some 140 hazardous compounds to prepare a risk management plan (RMP). The Department, through its consultant Camp Dresser & McKee Inc. (CDM), prepared this RMP which applies to the use of chlorine, which has a TQ of 2500 pounds, and is used for disinfection of wastewater at the WWTP, because the Department intends to have up to
10,000 pounds of chlorine on site. Because the chlorine system at the WWTP is an existing system, the Department is submitting the RMP to EPA by June 21, 1999.
The Department uses chlorine stored in 2000-pound pressurized steel cylinders for disinfection of wastewater. Under terms and conditions of its NPDES permit, the Department only uses chlorine in the disinfection process at the WWTP from approximately April 1 through October 15 each year. At any given time during this period, up to four such cylinders may be tied into the process, with an additional cylinder in storage ready to go on line. Chlorine is delivered to the WWTP on an as-needed basis. Although the chlorine exists as a liquid under pressure inside the cylinders, it is passed into the disinfection process as a gas through a series of pipes and valves at near ambient temperature and pressure, until it is injected into the liquid process stream and goes into solution to be applied at various points within the WWTP.
The Department has an active chlorine leak-detection system linked to an alarm and ventilation system in place and operational in those indoor areas of the WWTP where gaseous chlorine could likely be present.
The RMP summarizes the Department's RM Program that supplements the procedures described in other Town of Webster documents such as general administrative guidelines and safety and health manuals. The RMP addresses the Department's RM Program management procedures, hazard assessment, prevention program, and emergency response program developed in response to the Chemical Accident Prevention rule. Each major element of the Chemical Accident Prevention rule is addressed in the RMP in detail. The Sewer Superintendent is the primary person in the Department responsible for implementing the provisions of the Chemical Accident Prevention rule for the WWTP.
The Department conducted an analysis of chlorine release potential at the WWTP. This analysis presents results of the wor
st-case release scenario as required by 40 CFR 68.25 and an alternative-case release scenario as required by 40 CFR 68.28, and public receptors are potentially affected by each scenario. However, over the last five years, no release meeting the provisions of 40 CFR 68.42(a) has occurred at the WWTP.
The prevention program of the RMP includes process safety information, a hazard review, operating procedures, training, maintenance procedures, provisions for incident investigations, and provisions for internal compliance audits.
The Department assembled a variety of safety information related to chlorine and the equipment used to store and transfer it within the WWTP. Chlorine is an acute toxin that can cause respiratory distress at relatively low concentrations, and can even cause death at higher concentrations. The chlorine-handling equipment at the WWTP was designed to safely contain chlorine, but in the event of an accidental chlorine release, a chlorine detection and alarm syste
m will alert personnel at the WWTP to the need for an emergency response.
The Department conducted a hazard review of the chlorine process. The hazard review team consisted of WWTP personnel knowledgeable in process operation and maintenance and consultants knowledgeable in the hazard review process. The hazard review team used a "what-if" technique, and recommendations were compiled.
The Department has adopted standard operating procedures (SOPs) that provide system descriptions, specifications, and operating steps for the chlorine system. The SOPs address start-up, shutdown, inspections, temporary operation, emergency procedures, and troubleshooting. Maintenance SOPs rely on manufacturers' recommended approaches.
The Department has implemented a training program with guidelines for conducting regular, structured plant training for Department employees. Training record forms document the required training. The training records for all personnel associated with the covered pr
ocess appear in the training file kept at the WWTP.
The Department developed an approach to investigate and document actual releases of chlorine as well as "near-miss" release incidents. The RM Program contains the details of this approach.
The Department developed an approach to perform audits of the compliance of its on-going RM Program with the requirements of the Chemical Accident Prevention rule. Department personnel or the Department's consultant will conduct such audits at least every three years.
An emergency response program procedure documents the measures the Department will take to respond to an accidental release of chlorine. For all but minor releases of chlorine, the Department intends to rely on the Webster Fire Department for response to an accidental release of chlorine, including providing incident command, local area evacuation and shelter-in-place notifications, and coordination with other appropriate agencies. Department personnel are responsible for initi
al notification to the Fire Department of a release and for facility evacuation and accounting for WWTP employees in the event of a major chlorine release.