Frankfort Wastewater Treatment Plant - Executive Summary |
|
This Process Safety Management (PSM) Plan has been prepared for the Frankfort Utility Board for the City of Frankfort's Wastewater Treatment Plant (WWTP), located at 45 West County Road 100 North in Frankfort, Clinton County, Indiana. For report purposes, the WWTP will hereafter be referred to as Facility. The Facility currently stores chlorine used in their process at a rate above EPA RMP threshold quantity of 2,500 pounds. At any given time the maximum amount of chlorine stored at the Facility is 6,000 lbs. The Facility currently has 13 employees; 12 full time and 1 part-time. In addition, the Facility hires 2 seasonal employees during the summer months. At least one operator staffs the site 24-hours a day, 365 days a year. The chlorine gas withdrawal system (hereafter referred to as process) is used for disinfection of the plant effluent or tertiary filter influent or filtered water storage. The process including all chlorine storage, occurs in the chlorine room and consists of the following equipment: 7 1-ton Liquid Chlorine Containers; 7 Two 1-ton Container Weight Scale and Container Rack; 7 Overhead Hoist Equipment; 7 Two Vacuum Regulators; 7 Automatic Switchover Unit; 7 Three Flow Proportioners; 7 Three Injectors; and 7 Process Piping. Chlorine dosage relative to flow, is controlled by the flow proportioners and injectors. Each proportioner is controlled by a signal from the flow metering equipment at the effluent end of the chlorine contact chamber. Water flowing across the injector creates a partial vacuum that activates the diaphragm valve in the vacuum regulator. Chlorine gas is introduced into the system at the injector and carried on to the point of application. The normal point of chlorine application will be at the chlorine contact tank. Plant effluent chlorination is required on a continuous basis with the chlorine residual not to exceed 1.0 milligrams per liter (mg/L) at the point of discharge. Chlorine application at the tertiary f ilter influent or the filtered water storage tank, used to control bacterial activity, may be accomplished independent of the effluent chlorination. The offsite consequence analysis includes consideration of two chlorine release scenarios, identified as "worst case" and "alternative releases". The worst-case release scenario involves a failure of both on-line containers which are positioned on the weight scale for a maximum possible release of 2,500 pounds of chlorine. The offsite consequence analysis assumes a release of the entire amount of chlorine gas in a period of 10 minutes. EPA-mandated meteorological conditions, namely Stability F, wind speed of 1.5m/sec, average daily standard temperature (700F), and average humidity (65%) were used as well as consideration for an enclosure situation. Using the EPA's RMP Guidance for Wastewater Treatment Plants Reference Tables/ equations for a worst case scenario, results in a toxic endpoint distance of 2.6 miles and an estimated potenti ally affected population of 16,238. The alternative release scenario involves the sheering of the steel connections (transfer hose failure) connected to both on-line one-ton containers, possibly due to human error. The amount of chlorine released is 2,500 lbs, at an average rate over 2 hours (the duration of the release) of 21.0 lb/min. The estimated distance to the toxic endpoint is 1 mile with potentially affected residential population of 4,591. The Frankfort Wastewater Treatment Plant accidental release prevention program is based on a Process Safety Management Plan containing the following key elements: 7 Training of Facility operators; 7 Use of state-of-the-art process and safety equipment 7 Use of accurate and effective operating procedures 7 Periodic performance of a hazard review of equipment and procedures; and 7 Implementation of a hazard review and inspection program Chemical specific prevention steps include availability and use of self-contained breathing apparatus by the operators during delivery, connection, and disconnection of the chlorine supply. Additional measures include employee training, standard operating procedures, process equipment maintenance, and awareness of the hazardous and toxic properties of chlorine. No accidental releases of chlorine have occurred at this Facility in the past five years. The Facility has an emergency response program, which has been coordinated by the Frankfort Fire Department, and the Local Emergency Planning Commission. This program includes an emergency response decision tree and notification plan. Emergency response drills and drill evaluations are conducted. Emergency operation and response procedures are reviewed at that time. Several changes to improve safety were identified as a result of an audit and PHA recently completed for the Facility. Recommended actions will be implemented as part of the Facilities Prevention Program. |