City of Saginaw Wastewater Treatment Plant - Executive Summary |
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EXECUTIVE SUMMARY The City of Saginaw Wastewater Treatment Plant processes wastewater from several municipalities at its site at 2406 Veterans Memorial Parkway. The final phase of that treatment involves the disinfection of the Plant effluent, along with the removal of residual disinfectant, before discharging treated water to the Saginaw River. The WWTP uses chlorine for disinfection and sulfur dioxide for chlorine residual removal. These chemicals are stored in, and applied to the process from, one ton containers. Both of these chemicals are removed from their respective containers, and fed to their appropriate points in the treatment process, in their gaseous state. Both chlorine and sulfur dioxide are toxic, and could cause injury or death to persons who are exposed to the chemicals in high concentrations. In the event of a catastrophic failure, the possibility exists for off-site exposure. Although the Plant has operated for nearly 50 years with no serious accidents or off-site effects, it is only prudent to prepare for the unlikely event of a serious accidental release. The use and storage of hazardous chemicals is regulated by several government agencies, both State and Federal. These include the Environmental Protection Agency, the State of Michigan Department of Consumer and Industrial Services (MIOSHA), and the State of Michigan Department of Environmental Quality. In addition, the WWTP is required to make annual reports to local public safety officials and the Local Emergency Planning Committee. MIOSHA requires that all facilities which store or process certain quantities of hazardous chemicals prepare a Process Safety Management (PSM) plan. This plan requires a Process Hazard Analysis, regular audits, inspections, and updates. In addition, Plant employees who work with the processes are involved in formulating the plan, as well as plant supervisory personnel with recognized expertise in the processes and equipment. The PSM pl anning is intended to prevent or minimize leaks or discharges of hazardous chemicals which would pose a threat to on-site personnel. The City of Saginaw WWTP PSM plan is periodically examined and updated, with the most recent update occurring in July of 1998. Updates are triggered by changes in equipment or procedures, and require re-training of all employees who may work in the area where the chemicals are stored or processed. The plan must be audited every two years; the next audit is due in October of 1999. The PSM plan requires written procedures for all routine and non-routine operations involving the covered chemicals. In the process of preparing these Standard Operating Procedures, plant personnel examined existing procedures, looking for areas in which improvements could be made. Several minor changes were suggested and implemented. The PSM Process Hazard Analysis required a formalized approach to determining possible weaknesses in procedure or equipment. The PSM committee cho se to use a "what-if" analysis, in which each component or procedure was examined, and the consequences of possible failure were considered. In addition to these required programs, the WWTP has always had its own in-house safety program regarding these chemicals. Operations personnel, as well as a portion of the maintenance staff, have been trained in the hazards of the substances, proper handling, and emergency response. The chlorination and de-chlorination equipment is inspected hourly by the operator on duty, and operating conditions are documented. The chlorination/de-chlorination building at the WWTP consists of three rooms: chlorine room, sulfur dioxide room, and mechanical/electrical equipment room. All ton containers on site which contain any product are stored inside the respective chemical rooms until used. Both the chlorine room and the sulfur dioxide room are equipped with leak detectors, which trigger an audible alarm and visual alarm at a preset level. A lea k detection alarm is also sent to the plant SCADA system, where the alarm is logged on an alarm printer. The same leak detection set-point which sets off the alarm also actuates the roof-mounted exhaust fan and fresh air louvers in the chemical room where the leak is located. A second pre-set level on the leak detector actuates a solenoid which closes pneumatically actuated ball valves mounted directly to each containers feed valve, thus stopping any leak downstream of the container itself. The WWTP also has single-gas monitors for chlorine and sulfur dioxide for use by personnel as a back-up for the stationary leak detectors when working in the chemical rooms. The chemical piping between the containers and the pressure regulators is constructed of schedule 80 carbon steel pipe. Piping from the pressure regulators to the feed points, all of which operates under vacuum produced by the induction units at the respective feed points, is constructed from schedule 80 PVC pipe with a l ength of PVC flexible hose connecting to each inductor. The City of Saginaw WWTP is staffed 24 hours per day, 7 days per week by operations personnel. Five operations crews, each crew consisting of a foreman and 2 operators, work a swing shift. The 24 hour emergency contact number rings into the operations office. The operating foreman on duty will be the emergency contact person. Despite the precautions taken, plant personnel still prepare and train for the event of an accidental release. Operations and maintenance personnel practice regularly the donning and use of self contained breathing apparatus, which will allow them to investigate and mitigate small leaks in a timely fashion. Also, plant personnel, as well as Saginaw Fire Department personnel have trained on the use of the Chlorine Institute leak kit "B" to enable them to repair a leaking ton container. In the unlikely event of a major leak, the plant Emergency Response Plan requires notifying the Saginaw Fi re Department. The Fire Department has a Hazardous Materials Response team, the members of which receive extensive training in handling chemical leak situations. The leaders of this team are certified trainers, and have provided training to WWTP operations and maintenance staff, and this training is updated on an annual basis. In addition, Fire Department and WWTP personnel periodically stage joint exercises in which a leak is simulated, so that a coordinated effort can be made to handle the leak in a safe and timely manner. The Fire Department will determine the severity of the leak and, if necessary, will coordinate with the Saginaw Police Department to alert persons downwind of the need to evacuate or seek shelter. The City of Saginaw Wastewater Treatment Plant takes seriously its responsibility for the safety of its employees and neighbors. Efforts will continue to be made to operate our processes in the safest possible manner, and to strive to improve equipment and/or pro cedures where possible. |