Harwood's Mill Water Treatment Plant - Executive Summary
This Risk Management Plan (RMP) was prepared for the purpose of demonstrating compliance with the requirements of Section 112(r) of the Clean Air Act pursuant to the United States Environmental Protection Agency (USEPA) regulations contained in Part 68 of Code 40 of the Federal Regulations (40 CFR Part 68). Sections 68.1-68.220, Accidental Release Prevention Provisions. |
40 CFR Part 68 requires stationary sources with listed substances present in a quantity greater than the corresponding threshold quantity to develop and implement a risk management program that includes a hazard assessment, a prevention program, and an emergency response program. The risk management program is to be described in an RMP that is registered with USEPA, submitted to state and local agencies, and made available to the public. At the Harwood's Mill facility, chlorine, which is a listed substance, is stored in a quantity greater than its threshold quantity of 2,500 pounds (lb).
This RMP was prepared in acc
ordance with 40 CFR Part 68, Subpart G, 68.150-68.190. In accordance with 40 CFR Part 68.10(d)(2), since accidental releases of chlorine result in off-site impacts and chlorine storage operations are subject to the Process Safety Management (PSM) standard, Prevention Program 3 requirements apply to this facility.
The Harwood's Mill facility uses chlorine in its water treatment process for disinfection and destruction of disease-producing organisms that may be present in the water. Chlorine is stored at the Harwood's Mill facility as a liquid under pressure in one ton steel cylinders. These cylinders are stored inside of a building. The liquid chlorine is transferred from the cylinders to a chlorine evaporator. Upon vaporization, the chlorine is then sent to the chlorinators which control the chlorine dosage to the specific applications. The Harwood's Mill facility's maximum intended inventory of chlorine is 40 cylinders.
The Harwood's Mill facility's accidental release prevent
ion and emergency response procedures are based on the goal of storing and handling this substance in a manner that prevents exposure to employees and the nearby community. It is the facility's policy to adhere to applicable state and federal regulations.
In accordance with 40 CFR 68.25(a)(2), the Harwood's Mill facility is required to analyze and report in the RMP one worst-case release scenario that is estimated to create the greatest distance in any direction to an endpoint for chlorine. In accordance with 40 CFR 68.25(b)(1) and 68.25(c)(1), the basis for the worst-case release scenario is defined as the release of the greatest amount held in a single vessel. For the Harwood's Mill facility, the single largest chlorine storage vessel is a one ton cylinder. Since chlorine exists as a gas at ambient conditions, it is assumed that the entire contents of one cylinder, approximately 2,000 lb, would be released as a gas over a 10-minute period. The worst-case release scenario resul
ts in a distance of 0.9 mi to the toxic endpoint for chlorine.
In accordance with 40 CFR 68.28(a), the Harwood's Mill facility is required to evaluate at least one alternative release scenario for chlorine. The alternative release scenario is defined as a leak in a valve of the transfer line leaving the evaporator. This type of leak would last for a duration of approximately 3-4 minutes before it was recognized by facility personnel and mitigated. This type of release results in a choke flow of chlorine leaving the valve. The alternative release scenario results in a distance of 0.1 mi to the toxic endpoint for chlorine.
The Harwood's Mill facility, as part of its accidental release prevention program, requires both current and newly hired operators and maintenance personnel to complete and pass the facility's Personnel Qualification Standards (PQS). The PQS consists of training in the following subjects: operating phase, operating limits, safety and health considerations, and s
afety systems and their functions. The Harwood's Mill facility also conducts equipment inspection and maintenance activities as part of their accident release prevention program.
The Harwood's Mill facility has an existing emergency response plan that incorporates emergency response and coordination procedures for chlorine releases. The local fire department and local emergency planning commission are included in this plan.
The Harwood's Mill facility conducted a review of the process hazards analysis in March 1999. As a result of this PHA, the following changes are expected to be implemented at the facility by December 1999: installation of a chlorine scrubber