City of Bethlehem Water Treatment Plant - Executive Summary |
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EXECUTIVE SUMMARY City of Bethlehem Water Treatment Plant Accidental Release Prevention and Emergency Response Policies The facility has written Standard Operating Procedures (SOPs) in place for operation and maintenance of the chemical feed system, employee training and emergency response. As a municipal agency, plant personnel work closely with appropriate agencies in the City of Bethlehem to assure safe operation of the plant, and expedient response in case of an emergency. Description of the Facility and the Regulated Substances Handled The City of Bethlehem ("the City") operates a water treatment plant, located in Lehigh Township, Northampton County, Pennsylvania. The toxic substance maintained as a part of the City's Water Treatment Plant is chlorine. It can be used for pre-chlorination and/or post-chlorination. The facility includes a Chlorine Storage Room, Chlorine Feed/Control Room and a Chlorine Scrubber Room. While the Chlorine Storage Room provides an area to sto re up to twenty (20) one-ton containers, only sixteen one-ton containers are stored under normal conditions. Eight (8) one-ton containers can be manifolded to the chlorine supply at one time and are stored on four container scales to keep track of inventory by weight loss. The containers are connected to the manifold header by means of a valve and yoke assembly along with a flexible connector. Under normal operating conditions all eight containers are connected to the system. The remaining containers are stored unconnected in the Chlorine Storage Room. Gaseous chlorine flows under pressure from the containers to a vacuum regulator. From the regulator, chlorine flows under vacuum by means of a remote eductor. The vacuum regulator between the pressurized and vacuum piping systems contains a gas inlet valve and an automatic switchover device. A pressure relief valve is located on the vacuum side of the switchover device. A loss of vacuum for any valve will automatically vent ga s to the atmosphere, if pressure develops. Four cabinet-mounted chlorinators are located in the Chlorine Feed/Control Room to meter chlorine flow; two for pre-chlorination and two for post-chlorination. Worst-Case and Alternate Release Scenarios The Risk Management Program Guidance (40 CFR Part 68) for Wastewater Treatment Plants (EPA, October 1998) was utilized for both of the above scenarios, since there is no EPA document specific to water treatment plants. Worst-Case Scenario A ten-minute release under worst case meteorological conditions (F stability, 3.4 mi/hr wind speed and 77 degrees F ambient air temperature ) was assumed for the worst-case scenario. A rural topography was used. A release of 2,000 lbs of chlorine (the entire contents of one container) was assumed, at a rate of 110 lbs/ min for 10 minutes. The approach assumes that enclosed releases only discharge 55% of the quantity released into the atmosphere. The distance to the toxic endpoint was estimated to be 2. 2 miles. It was estimated that a release under the worst-case scenario would affect 3,700 people. Alternative Scenario The Bethlehem WTP is equipped with an active mitigation measure, in the case of a chlorine leak. Online tanks are located in the Chlorine Storage Room, which vents to a scrubber system, which reduces the concentration to 1.9 ppm of chlorine prior to venting to the atmosphere. Because this exit concentration is below the toxic endpoint for chlorine (3 ppm), the alternative scenario results in no off-site impact. The lowest allowable units were entered into items 3.5 through 3.8 and 3.11 of the Submit report, since the program would not accept zero as a valid unit. Accidental Release Prevention Program and Chemical-Specific Prevention Steps The facility approaches release prevention by assuring that its containers, feed lines, valves and other mechanical apparatus in the chlorine supply system adhere to applicable ASTM and ANSI standards, as well as by providing training to its employees which allows them to safely and efficiently carry out their duties Five-Year Accident History There have been no releases during the entire operating life of the plant. The initial startup of the Water Treatment Plant was October, 1994 Emergency Response Program There are three chlorine gas detectors; one located in each room. They are checked on a monthly rotating basis (each detector is checked quarterly). These detectors continuously monitor for chlorine in these three locations. A chlorine level warning will sound at 1 ppm and a chlorine alarm will sound at 3 ppm. If there is a leak of chlorine detected in the Chlorine Storage Room above 3 ppm, the chlorine scrubber system will be activated. When this system is activated, the ventilation system will shut down and the air will be drawn out through the scrubber. The scrubber utilizes sodium hydroxide to react with the chlorine, rendering it harmless. The scrubber system can also be activated man ually by activating one of the scrubber activate buttons located in the Chlorine Storage Room. The scrubber has a capacity to neutralize 2,350 lbs of chlorine, with a single caustic charge. Because the facility is included in the community emergency response plan developed under 42 USC 1103, it is exempted from compliance with the emergency response program requirements at 40 CFR 68.95. Instead, in the event of a release, one of the facility's Emergency Coordinators will be notified. The Emergency Coordinator on duty will immediately notify the Northampton County Emergency Management Agency, the local Fire Department and other appropriate agencies. Facility personnel will not respond to accidental releases of regulated substances. Instead, the personnel on duty will activate the chlorine scrubber and notify other personnel at the WTP. If a release is not contained within the facility, the Site Emergency Coordinator (SEC) on duty will immediately notify the Northampton County Emerg ency Management Agency and the local Lehigh Township Fire Department. The Fire Official will act as the incident commander coordinator, and will assume responsibility for monitoring the release, assessing the impact on the area, and keeping a detailed log of all activities. Planned Changes to Improve Safety The facility is in the process of complying with all deficiencies outlined in the hazard review portion of the RMP. |