Somerset Water Service - Executive Summary
Somerset Water Service Water Treatment Plant, located at 5400 South Hwy 27, Somerset, KY, has one independent chlorine injection system. The chlorine storage and chlorination processes are located inside the chlorine process building. The system has one (1) one-ton container of chlorine on line and one (1) one-ton container of chlorine on standby at any one time. The system is operated under vacuum using gaseous chlorine. There is a Vacuum Regulator-Check Unit (Wallace & Tiernan 500 lb/24 hour capacity) which automatically shuts off the cylinder in the event of a break in the vacuum line. The chlorine supply system can automatically switch between the on-line and standby chlorine containers when the on-line container is depleted. |
The facility has a chlorine detector to monitor leakage in the chlorine storage/chlorinator room and a chlorine sensor is located at about twelve inches above floor level. The detector will automatically alarm at the facility and at the main control roo
The facility normally stores a maximum of 3 one-ton cylinders at the site at any one time. All cylinders are stored indoors in a building with doors, which seal. During chlorine deliveries, the delivery truck backs up to the unloading area and the cylinders are taken off the truck via the facility's crane and placed upon the dock.
Normally, the chlorinator room is secured with doors that remain closed and locked except when the system is being inspected. Inspection takes place daily. All chlorine cylinders are stored indoors. If a chlorine leak is detected, the chlorine alarm will sound and the Operator will notify the Plant Supervisor and appoint a Standby Operator. The Operator and Standby will don the Self-Contained Breathing Apparatus (SCBA) and the operator will then investigate the cause for the alarm. The exhaust fans will be activated from the exterior of the building. The air inside the building is evacuated and fresh air is drawn into the building through
upper and lower vents respectively. The Standby will remain outdoors in contact with the Operator ready to call for outside assistance if needed. The Operator and the Standby are trained in chlorine safety and emergency procedures. The Operator will shut the chlorine cylinder. If the leakage is not stopped the Hazmat Team will be contacted. The exhaust fans will be turned off.
The Worst Case chlorine release for this facility assumes that a one ton chlorine cylinder ruptures during unloading outdoors in a rural area. The cylinder discharges a dense gas release under worst case meteorological conditions of F Stability and 1.5 meters per second and ambient temperature of 250C. All two thousand pounds contained in the cylinder are assumed released over ten (10) minutes. It is only presented for comparative purposes and for non-OSHA facilities to determine under which RMP Program Level the facility fits.
The Worst Case Impact Area is three (3) miles in radius (EPA CEPP Risk Man
agement Program Guidance For Water Treatment Plants EPA 550-B-98-010 October 1998). There are about 4,400 people living in the Worst Case release area who could be affected by this type of release. Located within this area are two schools (Burnside Elementary School and Somerset Community College), as well as eighteen churches. There are no day care facilities, nursing homes, or hospitals within this area.
The Most Likely case release assumes a release of chlorine occurs due to a pipe leak in the chlorine storage or chlorinator areas. In order to have a leak that emits chlorine outside of the facility, it is necessary to assume the chlorine alarm is activated and the automatic cylinder vacuum loss shut off fails. The alarm would sound and the facility's emergency response team would be at the location within a few minutes to shut the system down at the cylinder.
Under those assumptions, the most likely release case is assumed to be a steady-state leak of up to 5 pounds per minut
e of chlorine (either as a gaseous or a two-phase release) for 30 minutes (150 lbs). It should be noted that a completely filled one-ton cylinder has maximum gaseous discharge rate of about 500 pounds per day (0.35 pounds per minute). Significant gaseous discharges above this rate will result in the cylinder freezing up and the discharge stopped. The facility has only one (1) one-on cylinder hooked up to the header and a maximum discharge rate from that system could be 0.35 pounds of chlorine per minute. It is also assumed that the cylinder discharges a dense gas release under meteorological conditions of D Stability and 3.0 meters per second at an ambient temperature of 250 C.
The Most Likely Case Impact Area based upon the above conditions is a tenth (0.1) of a mile in radius (EPA CEPP Risk Management Program Guidance For Water Treatment Plants EPA 550-B-98-010 October 1998). It is estimated that there are 9 people living in the Most Likely Case release area who could be affect
ed by this release. There are no schools located within this area. There are no hospitals or parks located within this area. In fact most of this release would be contained on the Facility's property.
The Facility has not had an accidental release of chlorine from this covered process in the five years prior to the submission of this Risk Management Plan (RMP).