Cherokee Water Treatment Plant - Executive Summary
The facility covered in the Risk Management Program (RMP) includes the Cherokee Water Treatment Plant for the City of Longview. The process included in the RMP is the disinfection process using chlorine and anhydrous ammonia. Currently the plant uses one ton chlorine cylinders (2000 lbs). The chlorine system includes four cylinders mounted for use, with two cylinders on-line (4,000 lbs) and two cylinders ready for service on stand-by (4,000 lbs) when the other two are empty. Since the threshold quantity for chlorine is 2,500 lbs, this process is regulated by the current RMP rules. The ammonia system includes a 3,000 gallon steel pressure tank. The maximum capacity of the 3,000 gallon tank is approximately 15,000 lbs. The City stores 85% of the maximum tank capacity or a total of 12,750 lbs. The threshold quantity for anhydrous ammonia is 10,000 lbs. The facility handles several other chemicals and processes. These chemicals are either not on the list of regulated toxic substan |
ces or do not exceed the threshold limits.
A worst-case release scenario and an alternative release scenario were developed for both chlorine and anhydrous ammonia at the plant. The OCA Guidance Tables from the EPA Guidance Manual were used for the worst-case and alternative release scenarios for both chemicals. Mitigation measures were not considered in the analysis. The worst-case release scenario for both processes consists of release of the greatest amount held in a single vessel over a ten minute period of time. The chlorine scenario produced a distance to end-point of release of 4.3 miles. The ammonia scenario produced a distance to end-point of release of 2.12 miles. The alternative release scenario for the chlorine cylinders consists of failure of a 1-inch schedule 80 pipe connected to two 1-ton containers. The result is a distance to end-point of release of 0.24 miles. The alternative release scenario for the ammonia tank consists of leakage through a 0.5 inch diame
ter hole. The result is a distance to end-point of release of 0.21 miles. The alternative release scenarios were chosen to better represent a possible release event in accordance with the previous accidental release that occurred from problems with connections.
The prevention program for the plant consists of several different sections, including safety information, hazard review, operating procedures, training, maintenance, compliance audits, and incident investigations. The safety information, hazard review, and operating procedures sections are completed for both the chlorine and ammonia systems. The training, maintenance, compliance audits, and incident investigations sections are completed for the plant as a system. The safety information includes material safety data sheets for each chemical, maximum inventories, safe operating limits, equipment specifications, and codes and stardards for design. The plant maintains a form specifying the current safety information used and
documents any changes as they occur. The safety form must be updated at least every two years. The hazard review information includes the forms necessary for the reviews that will be performed at least every five years for the different processes. The operating procedures information includes standard operating procedures for initial startup, normal operations, temporary operations, emergency and normal shutdown, and startup following an emergency or normal shutdown. Forms are provided to document the procedures for the plant, including a chlorine checklist and chlorine change-over form. The training information includes certification that employees have been trained for the processes and equipment that they operate. Documentation is also kept for refresher training that must be provided at least every three years. The maintenance information includes a form to document testing and inspections. The forms also include verification and information documenting the development of
the maintenance program for the facility that must be updated at least every two years. The compliance audit information includes the forms necessary for the audit and the certification to be completed at least every three years. Incident investigation information includes the forms to be completed upon occurrence of an incident, including the Accident Investigation Report, Chemical Release Form, and Safety Team Report. The investigation summaries are maintained for at least five years.
The five-year accident history for the plant includes one accident. The accident involved a small chlorine release in 1997 reported as emergency operation of the chlorine header and flexible chlorine line freeze up. No one offsite was injured, but two treatment plant employee left the plant and were taken in for medical attention with assistance from the fire department. Policy changes were made in accordance with review of the 1997 accident. These changes included an equipment inspection form
including a statement of equipment condition and repair procedures. The log of monthly inspections and cleaning processes of protective equipment has also been changed to a daily use form in the SOP chlorine drum changing procedure.
The emergency response program includes the response program for incidental leaks as handled by plant employees and the program for major spills and/or releases as covered in the City of Longview's Emergency Response Program. The incidental releases include leaks encountered when installing the cylinders for use, dismantling the chlorine cylinders, and any minor release found upon inspection or testing of the equipment. Proper equipment is maintained at the plant for use in the incidental release situations. Major releases or problems encountered with the smaller releases will be handled by outside assistance. The plant is currently set-up to contact the City of Longview Fire Department for assistance with chemcial releases. The local Hazmat team w
ill then be contacted by the fire department if needed. The First Call emergency contact system is also available for persons in Gregg County. The fire department will iniate contact with the First Call program for emergency notification assistance.
The City of Longview Emergency Response Plan for Hazardous Material Incidents is identified in detail in the RMP with copies of the forms for emergency notification. These emergency notification forms include: Emergency Public Information Checklist for Hazardous Material Incident, Sample Radio/TV Message for Unidentified Spill/Release in Heavy Traffic Area, Sample Radio/TV Message for Low Hazard/Confined Spill/Release - No General Evacuation, Sample Radio/TV Message for High Hazard Spill/Release - In Place Sheltering, Sample Radio/TV Message for High Hazard Spill/Release - General Evacuation, and Sample Radio/TV Message for High Hazard Spill/Release - School Evacuation.
Currently the Cherokee Plant is scheduled for construction of im
provements to its chemical feed system this year. The new system is designed to incorporate a dual header feed system for chlorine. The improvements will allow more frequent and better inspection and testing of the chemical equipment. Specifications and information for the new equipment are contained in the RMP.