City of Weirton Water Department - Executive Summary
The U.S. Environmental Protection Agency (EPA) Risk Management Program (RMP) regulations 40 CFR Part 68, require facilities that have a regulated substance above the listed threshold quantities to develop a formal Risk Management Program. EPA also requires these facilities to register and submit a Risk Management Plan using RMP*Submit by June 21, 1999. The City of Weirton Water Department (Department) maintains quantities of chlorine at its water treatment plant above the RMP threshold quantity of 2,500 pounds and as such is subject to the requirements of 40 CFR Part 68. An off-site consequence analysis was completed to determine the RMP program level applicable to Departments chlorine system. Based on the worst-case release as defined by EPA the facility is subject to RMP Program 2 requirements.
The elements of the RMP are listed below:
X Process Hazard Assessment- Assess the potential impacts of worst-case and alternative release scenarios and compile a 5-year
X Prevention Program - Implement a comprehensive management program that affects a wide variety of operation, training, and maintenance activities.
X Emergency Response - Implement an emergency action program for the covered processes.
X Risk Management Plan - Register and submit an RMP plan that includes an executive summary, RMP data elements, results of the hazard assessment, and summarizes how all other requirements are met. Plan to be submitted to EPA by June 21, 1999.
The information presented in this section is intended to describe the elements of the Departments Risk Management Program. The format of the section corresponds to the executive summary data elements as dictated in 40 CFR Part 68.155 Executive Summary Section. A copy of the RMP plan submitted to the EPA is located in Appendix E.
Executive Summary Data Elements
According to EPA guidance the executive summary must include a brief descripton of the facilty's Risk Management Program. The fol
lowing sections list each of the required executive summary data elements by rule citation. This information is also included as part of the EPA submittal plan which is included in Appendix E.
68.155(a) Accidental Release and Emergency Response Policies
The Department has operated their chlorination system without incident since its initial operation. This successful operating record is due to the Departments commitment to training programs, operating procedures, and maintenance activities. The Department has consistently updated its policies and provided the necessary personnel training to enhance the safety of the operations at the water treatment plant.
68.155(b) Stationary Source and the Substance Handled
The Department operates a water treatment plant located adjacent to the Ohio River having a design capacity of approximately 4 million gallons per day (mgd). The supply source of raw water comes from the Ohio River and Rainey wells located adjacent to the plant. The plant
is located in the City of Weirton and supplies potable water to residential, commercial and industrial users in the Weirton metropolitan area and portions of Washington County, Pennsylvania.
Chlorine, for disinfection purposes, is supplied in 1-ton containers. Two containers are usually on line at any one time. Typical usage ranges from 100 lb./day (min.) to 25 lb./day (max.). The average feed rate is typically 125 lb./day. The ton containers are stored in a block building that is secured to prevent unauthorized access. A chlorine leak detector is located within the building and sounds an audible alarm and energizes an emergency beacon when activated.
68.155(c) Offsite Consequence Analysis
One worst-case release scenario and one alternative release scenario was assessed for the chlorine process. To ensure a common basis for comparisons EPA defined the worst-case scenario as the release of the largest quantity of a regulated substance from a single vessel or process line that res
ults in the greatest distance to an endpoint. The alternative release rate is a release that is considered more reasonable or "more likely." Active mitigation measures can be used in determining the alternative release scenario while the worst-case scenario only allows consideration of passive mitigation measures.
The toxic endpoint for chlorine has been defined by EPA to be 0.0087 mg/L (3 ppm). This airborne concentration that is used as the toxic endpoint is the maximum airborne concentration below which it is believed that nearly all individuals can be exposed for up to one hour without experiencing or developing irreversible or other serious health effects.
The distance to the toxic endpoint becomes a radius for a circle around the covered process. Residential population within the circle is required to be determined based on available census information. The population number is reported as part of the EPA submittal. This method greatly over estimates the population pote
ntially exposed to a single chlorine leak, because the chlorine plume would seek lowest elevations in the direction of the prominent winds. Since wind direction cannot be anticipated for an accidental release, EPA mandated the circle estimation method. The area around the Departments plant is urban. The environmental receptors include schools, businesses, recreational areas, churches, and residential areas. Environmental receptors were determined using LandView III Environmental Mapping software and USGS topographic maps (Weirton, WV, 1994; Steubenville East, OH, 1978; Knoxville, OH,1984).
Release scenarios and distances to toxic endpoints are discussed in more detail in the subsequent paragraphs.
Worst-Case Release Scenario
Worst-Case Release Scenario is determined in accordance with the requirements provided in 40 CFR 88.22 and 40 CFR 68.25(b,c).
As described in USEPA 40 CFR Part 68.25(b) the worst-case release shall be the greater of the following:
1. The greatest amount hel
d in a single vessel or
2. The greatest amount in a pipe.
For the chlorine process at the Departments water treatment plant the worst-case release will occur if a one-ton cylinder (maximum amount held in a single vessel) of chlorine ruptures and its contents escape to the atmosphere in 10 minutes. In the event the one-ton cylinder would release its entire contents to the atmosphere in 10 minutes the release rate would be 200 pounds per minute. The toxic endpoint worse case scenario release distance of 1.3 miles was taken from the EPA Risk Management Program Guidance Document, Exhibit 4-4, Distance to Toxic Endpoint for Chlorine.
The residential population within the 1.3-mile radius of influence was determined to be approximately 9,900 individuals. The population was determined using the LandView III Environmental Mapping Software. This software is distributed by the U.S Department of Commerce and recommended by the U.S. EPA for use in preparing Risk Management Plans. A map showin
g the impact zone radius is included in Appendix F.
Alternative Release Scenario
One alternative release scenario was evaluated for the chlorine process per USEPA 40 CFR 68.165(a)(2). The alternative release scenario considered is in accordance with the guidelines provided in 40 CFR 68.22 and 68.28.
The scenario for the alternative release follows:
The alternative release scenario is defined as the scenario that is most likely to occur in the event of a chlorine release. For the Departments water treatment plant, this release would be a gas leak resulting from a valve, connection, or process tubing equipment failure. Once the concentration in the chlorine building reaches 0.4ppm, the chlorine alarm would sound and the Plant personnel would initiate their response procedures. This scenario assumes the maximum amount of chlorine is released before any mitigation procedures can be performed.
The alternative release scenario is based upon a flashing liquid release through a 5/16" h
ole (valve body). The toxic endpoint of 0.30-miles is based on a release rate of 240 lb./min., D Stability and a wind speed of 3 meters per second. The toxic endpoint was taken from Exhibit 4-13 from the EPA Risk Management Program Guidance Document.
The City of Weirton Water Department is located in a semi-industrialized area on the Ohio River. While the 0.30-mile radius does extend across the river and into Ohio, the amount of residences in that area is minimal. The total residential population within the alternative release scenario was determined to be approximately 290 individuals using the LandView III Environmental Mapping software. A map showing the distance to the toxic endpoint is included in Appendix F.
68.155(e) Five-year Accident History
The chlorination facility has been in place since the 1960's. No accidents, as described under 40 CFR 68.42(a), have occurred at this facility since it began operation.
68.155(f) Emergency Response Program
The emergency response pr
ogram established by Department does not require personnel to act as the site incident commander. In the case of an incident the City of Weirton Fire Department becomes the incident commander and assumes the role of directing response activities including any community emergency evacuation measures. Fire department staff has the appropriate training for responding to an accidental release of chlorine. The facility's Emergency Response Planning and Response procedures are presented in the section entitled Emergency Planning and Response. The City's Emergency Disaster Plan and Resource Handbook is located in Appendix D.
68.155(g) Safety Improvements
The Department is currently in the process of evaluating the recommendations from the Process Hazard Review completed in May 1999. Recommendations include the following:
X Replace the wood framed roof of the chlorine building with non-combustible material, such as precast concrete.
X Install a guardrail on the exposed side of the build
ing adjacent to the plant access road to protect the building form vehicular impact.
X Replace the single entrance door with one with a viewing window to allow observations to be made from outside of the building. Replace the existing door hardware with panic hardware.
X Adequately label the piping and valves associated with the chlorination system.
It is anticipated that the above improvements will be completed within 12 to 18 months after review of the current City and Department budgets. Any improvements made in response to the recommendations will be documented and added to the RMP documentation.
As part of the Departments commitment to safety and respect for the hazards associated with handling and storing chlorine, the Department had an existing chlorine management system in place prior to the EPA RMP mandate. To comply with RMP, the Department re-evaluated their current system for handling chlorine and updated and modified elements as necessary. The RMP*Submit
satisfies the Departments requirement to register and provide the EPA a summary of their Risk Management Program for the chlorine system.