City of Avenal Water Treatment Plant - Executive Summary |
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The accidental release prevention and emergency response policies at this facility This facility stores and handles chlorine, which is considered hazardous by EPA. Like many other chemicals, chlorine is beneficial in small doses (diluted in drinking water to disinfect and improve quality) and dangerous in large doses. Only qualified personnel, properly trained in appropriate operating procedures, are allowed to handle equipment associated with our chlorine systems. We are committed to safety in all aspects of our operation, and the chlorine storage and handling is no exception. It is our policy to adhere to all applicable Federal, State, and Local rules and regulations, at a minimum. Our emergency response program includes procedures followed by all employees for notification of the local emergency services department and the facility utilities supervisor. Additionally, an extensive chlorine detection and monitoring system automatically shuts down the system in the case of malfu nctions, and automatically calls/pages facility personnel. This facility and the regulated substances handled The primary purpose of this facility is to supply potable water to the City of Avenal. Water is drawn from the California Aquaduct and is disinfected and treated to remove bacteria, algae, and other microorganisms. The handling of chlorine at this facility is limited to delivery and change-out of one-ton steel cylinders. Access to our facility is restricted to facility employees, authorized management personnel, and authorized contractors. Chlorine is the regulated substance used at this facility to destroy pathogenic micro-organisms, oxidize undesirable elements such as iron and manganese, and reduce some tastes and odors. The maximum amount of chlorine stored at this facility is 6,000 pounds, distributed among two water treatment plants. The worst-case release scenario(s) and the alternative release scenario(s) Worst Case Release Scenario The worst-case release s cenario assumed that the total quantity of chlorine would be released from the single largest vessel (one-ton cylinder) over a period of ten minutes as required by CalARP Regulations, Section 2750.3(c)(1). The chlorine cylinders are housed in an enclosed building, which acts as a passive mitigation system; however, the effect of the building was not included in this analysis at this time. This facility is located in a remote area, described by rural conditions (for modeling purposes). Failure of the largest storage cylinder on site when filled to capacity would release 2,000 pounds of chlorine. The worst-case scenario assumes that the entire contents of 2,000 pounds are released as vapor, equidistant in all directions until the toxic endpoint is reached (concentration falls below 3 ppm). Utilizing look-up tables found in Exhibit 4-3 of the EPA document, Risk Management Program Guidance for Wastewater Treatment Plants (40 CFR Part 68), the estimated distance to toxic endpoint for a 1-ton cylinder in rural conditions is 3.0 miles. Written safe unloading procedures are utilized at this facility which requires that at least two persons participate to ensure that all possible safety precautions are taken. A worst-case release, like the one described above, is highly unlikely at this facility. Alternative Release Scenario The alternative release scenario more likely to occur at this facility is a 5/16-inch valve failure on a 1-ton container. Utilizing Exhibit 4-15 of the EPA document, Risk Management Program Guidance for Wastewater Treatment Plants (40 CFR Part 68), the estimated distance to toxic endpoint for a vapor release through a 5/16-imch hole in rural conditions with atmospheric stability class D is 0.2 miles. The general accidental release prevention program and chemical-specific prevention steps This chlorine storage and handling facility will comply with California's and EPA's Accidental Release Prevention Rules, CalARP and 40 CFR 68. This facility stores and handles chlorine for onsite treatment of water. Onsite storage is maintained at a minimum utilizing pre-filled sealed one-ton cylinders. Chlorine is not filled on site. The chlorine systems at this facility were designed and constructed in accordance with good engineering practices and regulations in place at time of construction (Plant I - 1971, Plant II - 1986). The chlorine gas is injected for use via a vacuum piping system with a venturi injector. This minimizes the potential of leaks to the atmosphere. All employees who handle any of the chlorine equipment have been thoroughly trained utilizing facility and industry specific guidelines. The five-year accident history This facility has had no reportable accidents associated with the chlorine storage and handling in the last five years. The emergency response program This facility's emergency response program is included in the community written emergency response plan. Local emergency providers will be called in the case of an emergency. Local emergency providers have periodically visited this facility and are familiar with the associated hazards. Representatives from the Avenal Fire Department conducted a site visit on May 11, 1999. Planned changes to improve safety There are no planned changes to improve safety at this time. Prior to this review, the facility was modified to allow shared use of enclosed, chlorine cylinders. This was an improvement to safety because the previous system required two separate chlorine staging and storage areas, and one was not protected by a building enclosure. Additionally, the previous system required more chlorine to be stored on site than was needed or practical for safety reasons. |