Douglasville (Bear Creek) - Executive Summary |
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Bear Creek Water Treatment Plant (BCWTP), located at 4930 Gray Road, Douglasville, GA, has one independent chlorine injection system. The chlorine storage and chlorination process is located within two adjacent rooms comprising the chlorine process building. The system has one (1) one-ton container of chlorine on-line and one (1) one-ton cylinder on standby at any one time. The system is operated under vacuum using gaseous chlorine. There is a Vacuum Regulator-Check Unit (Fisher and Porter Series 70-1700 Gas Dispensing System, 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 and chlorinator rooms. Chlorine sensors are located at twelve inches above floor level in both rooms. The detector will au tomatically alarm at the facility and at the main control room panel if a leak is detected. The BCWTP Facility normally stores a maximum of 4 one-ton cylinders at the site at any one time. All full cylinders are stored indoors in a building with doors that remain closed. The empty cylinders are stored outside the building. During chlorine deliveries, the delivery truck backs up to the unloading area. The building doors are opened and the chlorine cylinders are brought inside via a crane. Normally, the chlorine storage and chlorinator room doors remain closed except when chlorine is being unloaded. 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 then 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 bui lding 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 Fire Department will be contacted and the exhaust fan 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. T he Worst Case Impact Area is three (3) miles in radius (EPA CEPP Risk Management Program Guidance For Wastewater Treatment Plants EPA 550-B-98-010 October 1998). There are about 7,000 people living in the Worst Case release area who could be affected by this type of release. Located within this area are four (4) schools. These schools are Alexander Comprehensive High School, Dorsett Shoals Elementary School, Bill Arp Elementary School and The Kings Way Church School. Seven (7) Nurseries/Preschools are within this area. They are Mrs. Vivian's, Green Acres, Sike's, Kinder Care, Central Baptist Church, Prays Mill Church, and Water of Life Christian Academy. Other facilities within the Worst Case Impact Area are the Garden Terrace Nursing Home, Inner Harbour Mental Health Facility, and 5 Cemeteries. There are no hospitals or parks within the Worst Case Impact Area. The Most Likely release case assumes a release of chlorine occurs due to a pipe leak in the chlorine storage or chlori nator rooms. 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 on-duty staff would respond as the first-line of the emergency response. If the attendant could not stop the leak, the second line of the emergency response team would be at the location within a few minutes to shut the system down the cylinder. This team is inclusive of but not limited to the local Fire Station, Douglasville-Douglas County Water and Sewer Authority's Maintenance (Dispatch) Team, and Facility Superintendent. Under those assumptions, the most likely release case is assumed to be a steady-state leak of up to 5 pounds per minute of chlorine (either as a gaseous or a two-phase release) for 15 minutes (75 lb). 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 BCWTP has only one (1) one-on cylinder hooked up to the header and a maximum discharge rate from that system would 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). There are no people living in the Most Likely Case release area who could be affected by this release. There are also no schools located within this area. There are no hospitals, parks or other sensitive receptors located within this area. In fact most of this release would be contained on the Douglasville-Dougl as County Water and Sewer Authority 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). |