Upper Smith River Water Filtration Plant - Executive Summary |
|
EXECUTIVE SUMMARY a. The Henry County Public Service Authority's (PSA) accidental release prevention program involves three items: technology, management, and procedural practices. The PSA's emergency action plan involves coordination between plant personnel, management, and public safety responders. The Authority is committed to providing a safe-working environment for its employees and the communities, which it serves. b. Upper Smith River Water Filtration Plant (Philpott) is a water purification plant owned by Henry County and operated by the Public Service Authority (PSA). The plant is located in Bassett on Philpott Drive. The facility supplies water for Bassett, Stanleytown, Collinsville and the 57 west areas. The plant is rated at 4.0 MGD. Chlorine is utilized for disinfection. The operation uses and stores 6-1 ton cylinder on site. The existing chlorine system operates when the facility is manned. The chlorine system is monitored by two means 1) electronic sensors with re motely activated audible and visual indicators and 2) visually by the operators. Alarmed conditions are responded to by a given protocol and trained personnel. c. The offsite consequence analysis includes consideration of two chlorine release scenarios, identified as "worst case release" and "alternative scenario". The first scenario is defined by EPA, which states that "the owner or operator shall assume that the maximum quantity in the largest vesselis released as a gas over 10 minutes" due to an unspecified failure. The alternative scenario is defined as "more likely to occur than the worst-case release scenario". Atmospheric dispersion modeling charts were referenced to determine the distance traveled by chlorine release before its concentration decreases to the "toxic endpoint" selected by EPA of 3 ppm, which is the Emergency Response Planning Guideline level 2 (ERPG-2). This is defined by the American Industrial Hygiene Association (AIHA) as the "maximum airborne concentrati on below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms which could impaired an individual's to take protective action." The residential population within a circle with a radius corresponding to the toxic endpoint distance has to be defined; "to estimate the population potentially affected". The worst-case release scenario at the Philpott plant involves the failure of 1-ton cylinder (2000 lbs. of chlorine). The offsite consequence analysis for this scenario was performed for two sets of conditions. The first set followed conditions pre-defined by the EPA, namely release of the entire amount as a gas in 10 minutes, use of the one-hour average ERPG-2 as the toxic endpoint, and consideration of the population residing within a full circle with radius corresponding to the toxic endpoint distance. EPA set these conditions to facilitate the performance of the of fsite consequence analysis. EPA-mandated meteorological conditions, namely Stability F and wind speed of 1.5 m/sec. When atmospheric dispersion modeling for the worst case scenario was performed using the EPA assumptions, a distance to toxic endpoint of 1.3 miles and an estimate of industrial and residential population potentially affected is 3400. Population density was obtained through the Planning & Mapping department of Henry County, which supplied the addresses of the industries and the residents within the circular area. The alternative release scenario involves the break of a = inch pigtail flexible connector with an amount released is 37 lbs./min. The toxic endpoint distance to ERPG-2 is .1 miles and the estimated of residential population potentially affected is 10. d. The Authority's prevention program is based on following items 7 Training of operators 7 Maintenance program 7 State of the art process and safety equipment 7 The use of self-contained breathing apparatu s (SCBA), worn by the operators during connection/disconnection of chlorine supply, awareness of the hazardous and the toxic properties of chlorine, and presence of chlorine detector. e. No accidental release of chlorine has occurred at this facility in the past five years. f. The facility has an emergency action plan, which has been coordinated with the Public Safety Director in charge of the fire and rescue for Henry County and the Local Emergency Response Planning Committee (LEPC). This program includes an emergency response notification plan. g. The treatment operations of the PSA are in the process of change and reassignment. Many of the existing processes are and will be evaluated for effectiveness and improvement. The PSA is always upgrading equipment and reviewing its operations to insure that it's in compliance with the current State and Federal regulations. |