City of Easton Water Treatment Plant - Executive Summary |
|
EXECUTIVE SUMMARY Located in mideastern Pennsylvania, the City of Easton is the county seat of Northampton County and is an industrial and commercial center with approximately 26,000 residents. The City of Easton is located at and around the confluence of the Lehigh River and the Delaware River, which is the border between Pennsylvania and New Jersey. The City of Easton maintains one water treatment plant (WTP) along the Delaware River, which was built in 1932 and is capable of treating 12 million gallons per day to the level required by the Pennsylvania Department of Environmental Protection (PADEP) and the Environmental Protection Agency (EPA) for use as community drinking water. All incoming water is disinfected by using chlorine to kill any pathogenic organisms as part of the treatment of the surface water that is converted to drinking water. A maximum of 8 one-ton containers (16,000 pounds) of chlorine may be stored onsite at any time, with 1 chlorine container in use at any given time. The containers are located in a brick building designed specifically and solely for the safe movement, storage and use of chlorine. The City of Easton WTP's accidental release prevention program is designed to ensure that the facility operates in compliance with the RMP Rule and with industry standards of performance, such as the guidance documents written by the Chlorine Institute. The prevention program is based on the following key elements: * High level of training of the operators * Preventive maintenance program * Use of state-of-the-art process and safety equipment * Use of accurate and effective standard operating procedures, written with the participation of the operators * Performance of a hazard review of equipment and procedures * Implementation of an auditing and inspection program Preventive maintenance is regularly scheduled and performed. Trained, experienced vendors clean, service and replace pipes, valves, chlorinators, rotameters and other equipment , as needed. Chemical-specific prevention steps include the availability of self-contained breathing apparatus (SCBA), worn by operators during connection/disconnection of chlorine supply, awareness of the hazardous and toxic properties of chlorine, and the presence of chlorine detectors. Chlorine gas is fed into the treated water with vacuum operated equipment, which offer the safest operation for low capacities. Piping and connections are kept to a minimum for safety. The piping was designed to be the shortest necessary length, and is properly supported and protected from risks of excessive heat or fire. The City of Easton WTP is not required to maintain a site-specific emergency response program, as defined by OSHA and EPA. However, it does have an Emergency Plan which has been coordinated with the LEPC, which gives specific details regarding emergency contacts, potentially affected areas, evacuation routes, and other information regarding the WTP. The WTP would contact the l ocal fire department and the Northampton County Local Emergency Planning Committee (LEPC) in the event of an accidental release, since it does not train its employees to handle such an emergency. The offsite consequence analysis includes consideration of two chlorine release scenarios, identified as "worst case release" and "alternative scenario". The first scenario is defined by EPA, which states that "the owner or operator shall assume that the ... maximum quantity in the largest vessel ... is released as a gas over 10 minutes," due to an unspecified failure. EPA also requires the assumption of worst-case atmospheric dispersion modeling conditions in order to be conservative and ensure public safety. The alternative scenario is defined as "more likely to occur than the worst-case release scenario". The worst-case scenario for an accidental release of chlorine is the catastrophic failure of a one-ton container. The toxic endpoint selected by EPA for chlorine is 3 parts per milli on (ppm), which is defined by the American Industrial Hygiene Association (AIHA) as the "maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action". This is the Emergency Response Planning Guideline Level 2 (ERPG-2). The residential population within a circle with a radius corresponding to the toxic endpoint distance has to be defined "to estimate the population potentially affected". When atmospheric dispersion modeling for the worst case scenario was performed using the EPA assumptions, a distance to toxic endpoint of 1.0 miles and an estimated residential population potentially affected of 6,400 was obtained. The building that houses the containers was considered as a passive mitigation system to reduce the potential risk. The alternate-case release scenari o is identified as a major leak caused by a bad valve, a poor connection, or a piping failure. This scenario was selected as "a more likely to occur than the worst-case release scenario" based on the past history of chlorine releases at this facility and at other WWTPs that are similarly designed. When atmospheric dispersion modeling for the alternate scenario was performed, a distance to toxic endpoint of 0.2 miles and an estimated residential population potentially affected of 250 was obtained. In addition to being enclosed in a building (passive mitigation) when the containers are in use, active mitigation measures in place to prevent and minimize releases include ambient chlorine monitors and a remote vacuum piping system, which would significantly reduce the amount of chlorine released in the case of a leak. EPA's innovative "Community Right-to-Know" software tool Landview III, along with database extracts of 1990 Census information and other sources were used to analyze the e stimated residential population for the worst-case scenario. An aerial photograph was used to count residences and confirm the estimated residential population in the alternate case scenario. There have been no accidental releases of chlorine in the past five years. Based on the hazard evaluation, the compliance audit, and other actions taken to prepare this RMP, a few areas were identified for improvement and changes were made to improve safety at the facility. This included the following: * Updating the Material Safety Data Sheet for chlorine; * Writing a standard operating procedure for connecting and disconnecting containers; * A more formal documentation system for employee training; * Revising the preventive maintenance procedures; * Developing an Emergency Action Plan. |