Marcellus Water Treatment Plant - Executive Summary |
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ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RELEASE POLICIES AT FACILITY - The Onondaga County Water Authority (OCWA) has prepared this submittal under the requirements of the Risk Management Planning (RMP) Program (40 CFR 68). OCWA is committed to ensuring the safety of their employees, local residents, and potential environmental receptors through the implementation of safe chlorine utilization practices, procedures, and measures. FACILITY DESCRIPTION AND REGULATED SUBSTANCES HANDLED - OCWA utilizes chlorine in bulk (1-ton chlorine cylinders) at their Marcellus Water Treatment Plant (WTP) for water disinfection. At the Marcellus WTP, the water is treated using polyaluminum chloride (PAC) and powdered activated carbon (PACT), followed by mixed-media filtration. The Marcellus WTP has a design capacity of 20 million gallons per day (MGD), however, the facility is typically operated well below this capacity. Within the Marcellus WTP, chlorine can be administered at three locations , as follows: (1) at the raw water supply; (2) at the mixed-media filters; and, (3) at the potable water supply. The plant uses chlorine for disinfection, taste and odor control, and for maintaining chlorine residuals within the water distribution system. The Marcellus WTP operates 24-hours a day, seven days a week. The facility is manned 16 hours per day (from 7 a.m. to 11 p.m.) using two shifts (facility is unmanned from 11 p.m. to 7 a.m.). Alarms at the Marcellus WTP are connected to an autodialer system and/or the Supervisory Control and Data Acquisition (SCADA) system which is located at OCWA's Mattydale, New York Northern Concourse operation (OCWA's Northern Concourse facility is manned 24-hours a day). Access to the facility is restricted by fencing. The only RMP-"regulated" substance utilized at the facility is gaseous chlorine. The facility maintains a maximum of 24,000 pounds (twelve 1-ton cylinders) on hand at any given time. Typically, OCWA maintains no mor e than 20,000 pounds of chlorine at the Marcellus WTP (a total of ten cylinders). WORST-CASE AND ALTERNATE RELEASE SCENARIOS - As a requirement under the RMP Program, OCWA has evaluated potential impacts from chlorine releases (under both worst-case and alternate release scenarios). The planning distances and potential impacts of these release scenarios is discussed below. For the worst-case release scenario, OCWA has assumed a release of the contents of one cylinder over a period of ten minutes. Due to the fact that chlorine cylinders are handled for a short period of time outdoors (during cylinder delivery), OCWA has not accounted for any passive or active mitigation measures for this release scenario. The planning distance for such a release has been estimated at 3.2 miles (this distance has been estimated by air dispersion modeling, utilizing the ALOHA model). This release event would have the potential to impact both population and environmental receptors. OCWA has a n umber of mitigation controls in place which would reduce the probability or minimize the impacts of such an event (these measures are described in the section entitled, "General Accidental Release Prevention Program and Chemical-Specific Prevention Systems", below). For the alternate release scenario, OCWA has assumed that one of the chlorine cylinders develops a 0.1875-inch diameter hole (to be conservative, OCWA has assumed that the cylinder arrived at the facility leaking; no passive or active mitigation measures were accounted for). Under this scenario, the cylinder contents would evacuate over a period of approximately 23 minutes. The planning distance for such a release has been estimated at 0.4 miles (this distance has been estimated utilizing the EPA's "Risk Management Program Guidance for Wastewater Treatment Plants" guidance document). This release event would have the potential to impact population receptors. OCWA has a number of mitigation controls in place which w ould reduce the probability or minimize the impacts of such an event (these measures are described in the section entitled, "General Accidental Release Prevention Program and Chemical-Specific Prevention Systems", below). GENERAL ACCIDENTAL RELEASE PREVENTION PROGRAM AND CHEMICAL-SPECIFIC PREVENTION SYSTEMS - OCWA has implemented a number of passive and active mitigation measures in an effort to reduce the probability or minimize the impacts of a gaseous chlorine release. These measures include: (1) chlorine cylinders are maintained in a building which would contain minor releases and dramatically reduce the impacts of a catostrophic release; (2) OCWA has developed and implemented standard operating procedures (SOPs) for the delivery of chlorine cylinders and the testing and hook-up of chlorine cylinders; (3) OCWA has installed a leak detection system in the Chlorine Storage Room (the chlorine "sniffers" are tested on a routine basis, using hypochlorite); (4) the facility is equipp ed with heat sensitive monitors (the fire alarm system is connected to the facility's dial-out system; (5) OCWA maintains emergency response/safety equipment at the facility (equipment includes: air packs, chlorine cylinder repair kits, safety shower, eyewash station, and fire extinguishers); (6) chlorine cylinders have a number of design considerations aimed at reducing the likelihood of a significant, uncontrolled release (these include protective dome covers over the cylinder valve and fusible plugs to protect from overpressurization due to exposure to heat); (7) the Chlorine Storage Room is a non-smoking area (in addition, no flammable materials are maintained in the Chlorine Storage Room); (8) the Marcellus Fire Department has been notified of the presence of chlorine cylinders (OCWA has a coordination agreement with the Fire Department); (9) OCWA has developed and implemented a Process Safety Management (PSM) Program which aims at reducing the potential for a significant chlorin e release; (10) the facility maintains a back-up generator with automatic switchover capabilities (ensures uninterrupted electrical service of chlorine protective equipment); (11) the facility maintains a portable chlorine detector which can be utilized to define the extent of a plume in the event of a chlorine release; (12) all facility operators are certified and are familiar with the operation of the chlorine system and the use of the health and safety equipment; (13) OCWA has incorporated certain design and operational procedures to limit the potential for a chlorine release (e.g., all chlorine piping is chemically-compatible and properly supported; rotometers in the chlorinators are recessed to avoid damage due to impact; a vacuum eduction system is in-place to prevent the escape of chlorine gas; pigtail connections are replaced regularly; etc.); (14) the facility is manned 16-hours per day; during un-manned hours, alarms would sound at the SCADA system located at OCWA's Northern Concourse facility (which is manned 24-hours per day); (15) OCWA has implemented a Preventive Maintenance program for the generator, compressor, pumps, leak detection system; and, (16) chlorine cylinders are maintained within "chocks" in the Chlorine Room to limit the potential for impact/damage. These protective measures limit the potential for significant impact to the local population/environment. FIVE YEAR ACCIDENT HISTORY - OCWA has not had any accidents from their Marcellus Water Treatment Plant operations which would be "reportable" under 40 CFR 68.42 ("reportable" accidents are incidents which have resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries, evacuations, sheltering in place, property damage, or environmental damage). EMERGENCY RESPONSE PROGRAM - OCWA has established a coordination agreement with the Town of Marcellus Fire Department (Fire Department has agreed to respond to any incidents and provide notifica tions, as applicable, to local residents). In addition to the coordination agreement, OCWA has developed a formal "Emergency Response Plan" as an element of their Process Safety Management (PSM) Program. The following major elements are addressed in the "Emergency Response Plan": (a) escape routes and procedures; (b) procedures for post-evacuation employee accounting; (c) preferred means to report emergencies; (d) emergency coordinators; (e) outside clean-up contractors; (f) emergency equipment; (g) coordination agreement; (h) alarm systems; and (i) reporting requirments. In addition, facility personnel conduct spill response drills/training in accordance with the requirements specified under 29 CFR 1910.119. PLANNED CHANGES ON CHLORINATION SYSTEM - Through the implementation of their PSM Program, OCWA has identified a number of modifications (both equipment and procedural) aimed at providing additional safety of the chlorine system at the Marcellus WTP. These modifications have been/are currently being implemented. |