Drinking Water Treatment at Generation Station - Executive Summary
Introduction Muscatine Power and Water (MPW) has chosen to draft and use the same Executive Summary for all of its Risk Management Plans (RMPs). The summary contains general information that is common to all affected facilities as well as facility specific data. This approach offers an overall perspective of the util |
ity operation while providing the facility specific information required for each of the plans. Our purpose is to make it as convenient as possible for the reader of any of the four plans to have pertinent information regarding MPW's regulated substances program rather than information about only one of its facilities.
Accidental Release and Emergency Response Policies
Management's commitment to safety is stated in the MPW Strategic Plan overall planning philosophies that include promoting a safe working environment. Two examples of implementing this philosophy are the Safety Incentive Program and Accident Review Team. The Safety Incentive Program encourages total employee involvement in, and commitment to safety and health by recognizing and awarding employees who meet utility-wide safety goals. The Accident Review Team is a voluntary group of employees who review accident reports, investigate specific situations, and make recommendations to correct safety problems. More s
pecifically, this safety philosophy is exemplified in an accidental release prevention policy utilizing an approach that combines management strategies with technological controls and operating procedures. Management strategies include minimizing the amount and types of hazardous chemicals used/stored at the Generation Station. Operating procedures include hazard awareness training, and having emergency response plans to address accidental releases from each of the specific facilities. Technological controls include automated safety valves and vacuum operation of chlorine injection systems.
Facility Description and Regulated Substances Handled
MPW is a municipal water, electric and communications utility. The utility serves the city of Muscatine, Iowa (population 23,000) and certain adjacent surrounding areas. Regulated substances addressed by this plan are used at the MPW Generation Station and three drinking water treatment facilities. The two chemicals included in
the Risk Management Plan are chlorine (Cl2) and sulfur dioxide (SO2). Both chemicals are used for water treatment. Chlorine is used as a biocide and disinfectant. Sulfur dioxide is used for dechlorination. A list of the facilities with associated quantities of chemicals is shown in Table 1.
FACILITIES HOUSING RMP REGULATED SUBSTANCES
Facility Location Chlorine Sulfur Dioxide Comments
In Use Stored In Use Stored
Gen. Sta. / WWT 1700 Industrial Connector Rd. 2 9* 1 5* Cooling water
Building Muscatine, IA 52761 treatment
Gen. Sta. / Main 1700 Industrial Connector Rd. 2 2 0 0 Drinking water
Well Fld. Bldg. Muscatine, IA 52761 treatment
Grandview Ave. Highway 61 South Drinking water
Well Fld. Bldg. Muscatine, IA 52761 2 6 0 0 treatment
Progress Park 6300 49th St. South Drinking water
Well Fld. Bldg. Muscatine, IA 52761 2 3 0 0 treatment
* Five chlorine cylinders and four sulfur dioxide cylinders are stored outside, adjacent to the building in a delineated area. The number of stored cylinders may change seasonally depending on chlorine demand for cooling water treament.
Chlorine in the cylinders at all facilities is stored as a liquid under pressure, but is removed from and used in the vapor or gaseous state. Sulfur dioxide in the cylinders is also stored as a liquid under pressure, and is removed from and used in the vapor or gaseous state. Sulfur dioxide is a colorless liquid or gas with a characteristic, pungent, rotten egg odor. It can be in a liquid state at temperatures less than 14oF. Both chemicals are delivered by truck.
The Generation Station includes three electric generating units with ancillary equipment, and one of the facilities that treat drinking water. Chlorine is used to treat once-through condenser cooling water for each of the generating units. The water is withdrawn from and returned to the Mississippi River. Chlorine inhibits biofouling of the condenser tubes (biofouling restricts flow through the tubes and reduces thermal exchange efficiency). To be effe
ctive, the chlorine concentration in the cooling water is high enough that the water must be dechlorinated in order to meet the allowable chlorine discharge limit in the station National Pollution Discharge Elimination System (NPDES) permit. Sulfur dioxide is used for dechlorination.
A single building houses the equipment for both chlorination and dechlorination of the cooling water for all three generating units. Two rooms in the building are used for chlorination/dechlorination, the remaining areas are used for wastewater treatment. The smaller of the two rooms houses the control equipment. The other room houses the chlorine and sulfur dioxide cylinders. Only two chlorine cylinders and one sulfur dioxide cylinder are connected to the system at a time. The facility is normally unmanned, but laboratory personnel who operate the equipment, visit the facility daily. The facility has leak detection sensors for both chlorine and sulfur dioxide. The alarms for these senso
rs sound in the Unit 9 Control Room of the adjacent power plant building that is staffed 24 hours per day, 365 days per year. The alarm also generates a print out from the laboratory PLC that can be used to control the equipment remotely. When an alarm is activated, control room personnel contact hazardous response personnel to investigate the cause of the alarm and address any problem(s). The Generation Station has controlled access 24 hours per day.
Chlorine is also used to treat drinking water for area residents and businesses. The Main Well Field Drinking Water Treatment Facility at the Generation Station is a single building that houses a water analysis laboratory, control equipment, and process chemicals and equipment. Water treatment personnel use the facility during normal working hours on a dail
y basis. The building is equipped with a chlorine leak detection system that alarms in the utility System Control Center that is staffed 24 hours per day, 365 days per year in the Administrative/Operations Complex. This complex is at a different location than the Generation Station. When an alarm is activated, System Control personnel contact hazardous response personnel to investigate the cause of the alarm, and address any problem(s). Since this building is located at the Generation Station, it has controlled access 24 hours per day.
Two other drinking water treatment facilities are not located at the Generation Station. They are the Grandview Avenue Well Field Drinking Water Treatment Facility and the Progress Park Well Field Drinking Water Facility. These buildings house control equipment, and process chemicals and equipment. Water Production Operators visit both facilities daily. Both of these buildings are also equipped with a chlorine leak detection system that al
arms in the utility System Control Center that is staffed 24 hours per day, 365 days per year in the Administrative/Operations Complex. The detection systems also activates a warning light on the outside of the Grandview Avenue treatment building. When an alarm is activated, System Control personnel contact hazardous response personnel to investigate the cause of the alarm, and address any problem(s). Security at both facilities is maintained by locking the building whenever it is unoccupied.
Worst Case and Alternative Release Scenarios
The offsite consequence analysis evaluates scenarios that represent the EPA "worst case" and "alternative release" situations. Scenarios were developed for chlorine and sulfur dioxide releases from cooling water treatment and drinking water treatment facilities at the Generation Station, and the other drinking water treatment facility locations. MPW used RMP*Comp, the Environmental Protection Agency (EPA) software, to evaluate the scenario
The results of the "worst case" scenario's for chlorine and sulfur dioxide are the same. The "worst case" scenarios used a one ton cylinder released inside a building during a ten minute period. A building reduces the release rate to 110lbs./ min. This release affected an area within a 0.9 mile endpoint that contained an estimated residential population of 232 individuals.
The "alternative scenario" for chlorine is a leak from flexible pipe. When the release occurs inside a building at a rate of 8.4lbs./min. for 120 minutes, the 1,012 pounds released affect an area with an end point of 0.1 miles. None of the estimated residential population would be affected by this release.
The same "alternative scenario" was used for sulfur dioxide. The 3.5lb./min. release rate inside a building f
or 120 minutes produced 425 pounds. The results are the same as those for chlorine. The area affected has an endpoint of 0.1 miles, and none of the estimated residential population is affected.
General Accidental Release Prevention Program and Chemical Specific Prevention Steps
The MPW general accidental release prevention program incorporates the following elements:Comprehensive training including practical exercises.Utilization of experienced operating personnel including Lab Technicians (who operate the cooling water treatment system) and Water Production Operators (who operate the drinking water treatment facilities).A computerized maintenance management system to schedule and document preventive maintenance.Utilization of safety oriented and effective operating procedures that were developed with participation of the operators.Preparation of a hazard review of equipment and procedures.
Chemical specific release prevention steps consist of implementing procedure
s and utilizing equipment. Response personnel, who are primarily familiar with certain facilities, are oriented and cross-trained at the facilities with which they are less familiar. Hazard awareness training, utilization of PPE, and availability cylinder repair kits instills confidence in system operators. For example, wearing an SCBA and using the buddy system whenever making cylinder connections is less stressful. Equipment precautions include release detectors and chemical injection systems that operate under a vacuum.
Five-year Accident History
No accidental releases of chlorine or sulfur dioxide have occurred from the facilities identified in this plan during the past five years.
Emergency Response Program
MPW employs an Incident Command System (ICS) to manage emergency responses. The ICS establishes a specific structure for the multiple, simultaneous activities necessary to successfully control a hazardous materials incident. This approach provides for a
single person to be in charge of an incident. That person, identified as the On Scene Incident Commander (OIC) is responsible for the overall management of the incident and setting the goals and objectives at the scene. Depending on the magnitude and complexity of the incident, the OIC adds additional command staff positions such as a Safety Officer, Hazard Sector, Medical Support Sector, Plant Site/Security Control, Environmental, and Public Relations.
The procedures for implementing the previously described approach are contained in the MPW 29 CFR 1910.120(q) HAZWOPER Emergency Response Plan that the utility drafted. This plan was prepared as a parent document into which other, already existing, chemical specific plans could be incorporated. The utility has chemical specific emergency response plans for chlorine and sulfur dioxide. These plans establish procedures, assign responsibilities, identify assembly areas, address shelter/evacuation of the general public, explain
arrangements for medical treatment, list outside assistance sources, contain a utility equipment list, and specify training requirements. Response planning has been coordinated with the local fire department that is hazmat trained and a member of the Local Emergency Response Planning Committee (LEPC). A coordinated training exercise was held with the Muscatine Fire Department in 1998.
Planned Changes to Improve Safety
Several activities during the past few years have already enhanced the safety of using these chemicals and another measure will be implemented. Recent activities eliminated old chlorination equipment, centralized chlorination/dechlorination, eliminated a marginally secure chlorination facility, established equipment preventative maintenance routines (PM's) and instituted routine inspections.
A building housing chlorine cylinders and chlorination equipment for the two older generation units was abandoned and demolished. Cooling water for these units is now handled by a central facility that serves all three units. The old building was located in the Mississippi River levee adjacent to the units it served, but outside the station security fence. The age/integrity of the building compromised security to some extent. The current facility is in the secure area.
Preventive maintenance routines for equipment are initiated through the Generation Station computerized maintenance management system. Equipment includes SCBA's, shower/eyewash stations, and chlorination system tubing and valves.
Weekly inspections of selected equipment are conducted and findings are documented. Chlorine and sulfur dioxide sensor operation is verified and alarms are checked. Building ventilating fan operation is also checked.
A facility audit and inspection program
was recenly instituted as an effort to continually seek improvements that can be made in operating procedures, safety equipment, process equipment, etc. Representatives from the Water Division, Safety Department, Generation Station Laboratory, and Environmental Department will continue to conduct these reviews.I