Nearman Water Treatment Plant - Executive Summary
BPU NEARMAN WATER TREATMENT PLANT: |
Release prevention and emergency response policies
The Board of Public Utilities, Kansas City, Kansas (BPU) takes an active role in preventing accidental releases at it's Nearman Water Treatment Plant (WTP) by ensuring that its employees are properly trained in the safe operation and maintenance of processes subject to the Part 68 rule. This training includes the safe handling of regulated substances under the rule.
BPU has also developed and maintained a risk management policy that contains general safety rules. Though these rules do not specifically address the covered processes and their regulated substances, compliance with the general rules significantly reduces the potential for accidental releases of the regulated substances. This facility complies with industry-standard practices for water treatment plants that use ammonia and chlorine in bulk.
As for emergency response, BPU has established and maintains procedures for
emergency notification and action. These are reviewed with employees on a periodic basis and revised to accommodate changes in staffing when they occur. In general, BPU plant employees would deal only with releases of a small amount of a regulated substance. If the release is determined to be large or if the chemical is stored outside or has migrated outside from a release indoors, BPU would immediately notify the Fire Department.
BPU management understands its duty to provide a safe working environment at this facility and to take measures to prevent accidents that may have an effect on the surrounding community. This understanding is reflected in procedures described and referenced in this document.
Facility and regulated substance
BPU's Nearman WTP is a 36-million-gallon per day plant that treats raw water from underground wells in the Missouri River flood plain and provides drinking water to the community. It does this through a series of physical and chemical treatment op
erations that includes rapid mix and flocculation, sedimentation, filtration, and chlorine disinfection. The treated water, now ready for use by the public, is transferred to a large reservoir and pumped into the distribution system.
The regulated substances stored, handled, and used at this facility are chlorine and aqueous ammonia. The chlorine is stored in one-ton containers with a maximum intended inventory of 27 containers on site. All of the chlorine containers are stored inside of a building. The aqueous ammonia is stored in two 8,860-gallon tanks located outside but in a diked area to contain spills.
Worst-case and alternative release scenarios
The worst-case release scenario for chlorine involves one of the one-ton containers used in the process. Each can contain 2,000 pounds of chlorine. The rule for worst-case release analysis assumes all of the contents are released in 10 minutes. The scenario assumed a release of all the contents of the container during unloading a
nd thus outside of any enclosure, though the containers are normally stored inside of a building. No mitigative measures were considered.
For aqueous ammonia, the worst-case release scenario involves the release of all of the contents of a full 8,860-gallon tank in ten minutes. This would be 65,000 pounds of solution. Because the tank is located in an adequately sized diked area, this secondary containment would hold the entire contents of the full tank and the contained solution would evaporate over a period of time assumed to be one hour.
The alternative release scenario for chlorine based on the results of the hazard review conducted as part of the risk management plan (RMP) development, experience at other similar facilities, and industry experience. The choice for alternative release was a broken or disengaged flexible tubing from the container to the header, allowing chlorine to leak into the storage room. The conservative assumption was made that the chlorine scrubber does
not work as intended, but the enclosure of the storage room acts as passive mitigation. The actual release of chlorine gas from the tube is 15 pounds per minute. When the enclosure factor of 0.55 is used, the release rate to the atmosphere is calculated to be 8.3 pounds per minute for ten minutes, or a total of 83 pounds.
The alternative release scenario for aqueous ammonia was based on the results of the hazard review, experience at other similar facilities, and industry experience. The choice for alternative release was a fill hose rupture between the tanker truck and storage tank and outside of the containment area. It was assumed that auto shutoff valve fails but that the leak is manually stopped after two minutes. The total amount of solution spilled on the ground is 1,850 pounds. Through pooling and evaporation, the rate of gas release to the atmosphere is 46 pound per minute until all solution has evaporated.
For both analyses, the EPA's Risk Management Program Guidance fo
r Wastewater Treatment Plants was used.
Accidental release prevention program
The facility's prevention program for both chlorine and aqueous ammonia complies with EPA's 40 CFR part 68 rule for program 2 processes. To maintain this compliance, BPU has in place many procedural and technological safeguards. The procedural safeguards include an employee-training program and operating and maintenance procedures for those employees involved in operating the covered processes. The technological safeguards include controls, sensors, alarms, and industry-standard systems. All of these serve to prevent unintended releases of aqueous ammonia and chlorine.
Should the prevention program fail to prevent a release, the WTP is equipped with engineering controls designed to minimize the effect of the release on the surrounding community. For chlorine, the storage containers are kept inside of a building to mitigate the effects of a release. The plant also has a scrubber capable of neutralizing
one ton of chlorine, the amount stored in the largest single container onsite. The scrubber is maintained on a regular basis to ensure proper operation if needed during a chlorine release.
The aqueous ammonia tank is surrounded by a concrete secondary containment so that a spill of chemical will not flow away from the storage tank. As with chlorine, the equipment in the ammonia process is operated and maintained by personnel properly trained in the hazards of the chemical and the process.
Five-year accident history
Because this is a new facility, there is no accident history.
Emergency response program
This facility has established and maintains an emergency action plan that is coordinated with local response agencies, such as the Fire Department and local HAZMAT team. The goals of the plan are to protect onsite employees from the hazardous effects of the releases and to minimize the effects of releases on the general public. The program is routinely reviewed and updated to r
eflect personnel and regulatory changes. It is also submitted to the Fire Department for review and comment.
City employees handle incidental releases of chlorine and aqueous ammonia and are trained and equipped to do so.
Planned changes to improve safety
Ideas for changes to improve safety are actively sought from employees. Employee meetings that focus on safety issues are held regularly. Employees are encouraged and trained to recognize hazards and present ideas to eliminate them or to minimize the potential consequences of those hazards.
During the development of the risk management plan, hazard reviews were conducted with key employees to meet the prevention program requirements. During these sessions, recommendations were made for the purpose of improving safety and preventing accidental chemical releases. Each recommendation has been or is being considered and evaluated for implementation. This evaluation process will provide all affected employees with a heightened awar
eness of safety issues related to the covered processes.