Pitman Creek Wastewater Treatment Plant, Somerset - Executive Summary |
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Pitman Creek Wastewater Treatment Plant, located at 475 Pitman Creek Road, Somerset, KY, has one independent chlorine and one independent sulfur dioxide injection system. The facility normally has a maximum of 2 one-ton chlorine cylinders and four (4) 150 pound sulfur dioxide cylinders at the site at any one time. All cylinders are stored in the chlorine feed room. Also, the chlorination and sulfur dioxide injector processes are located inside the chlorine feed room. The chlorine 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. The chlorine cylinder feeds a Fisher & Porter Vacuum Regulator and Flow Controller which automatically shuts off the cylinder if there is 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 sulfur d ioxide system has one (1) 150 pound container of sulfur dioxide on line and one (1) 150 pound container of sulfur dioxide on standby at any one time. The system is operated under vacuum using gaseous sulfur dioxide. The sulfur dioxide cylinder feeds a Fisher & Porter Vacuum Regulator and Flow Controller which automatically shuts off the cylinder if there is a break in the vacuum line. The sulfur dioxide supply system can automatically switch between the on-line and standby sulfur dioxide containers when the on-line container is depleted. Since the quantity of sulfur dioxide stored at the facility is below RMP thresholds, toxic release scenarios are not reported for this chemical. However, the facility's RMP plan covers both chlorine and sulfur dioxide. The facility has chlorine and sulfur dioxide detectors to monitor leakage in the chlorinator/injector room. The sensors are located at about twelve inches above floor level. The detectors will automatically alarm at the Facility and at the main control room panel. 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 into the chlorine feed room. Sulfur dioxide cylinders are rolled out of the truck into the chlorine feed room. Normally, the chlorinator/injector room is secured with doors that remain closed except when the system is being inspected. Inspection takes place daily. If a chlorine/sulfur dioxide leak is detected, the respective alarm will sound and the Operator will notify the Plant Supervisor and appoint a Standby. 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 contac t 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 Pulski County LEPC will be contacted and the exhaust fans will be shut down to try and contain the leak within the building. The Worst Case 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 miles in radius (EPA CEPP Risk Management Program Guidance For Wastew ater Treatment Plants EPA 550-B-98-010 October 1998). There are about 6.500 people living in the Worst Case release area who could be affected by this type of release. Located within this area are five schools (Saint Mildred's School, Somerset-Pulaski Memorial School, Parker School, University of KY Community College, and Ferguson School), as well as five churches. There are no child day care facilities, no hospitals, and no nursing homes. The Most Likely case release assumes a release of chlorine occurs due to a pipe break in the chlorine feed room. 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 the system. Under those assumptions, the most likely release case is assumed to be a steady-state leak of up to 5 pound s per minute 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 Wastewater Treatment Plants EPA 550-B-98-010 October 1998). It is estimated that there are 4 people living in the Most Likely Case release area who could be affected by this release. There are no schools located within this area. Also, 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). |