Haskins Creek Water Treatment Plant - Executive Summary
RISK MANAGEMENT PLAN |
McMinnville Water and Light is a public utility that provides water and electricity to McMinnville, Oregon. McMinnville is a community of approximately 24,000 people in northwest Oregon.
McMinnville Water and Light is committed to producing very high quality water at a low cost. To meet these goals all systems must be functioning properly, procedures must be followed, and employees must complete their work as safely as possible.
The water system is a gravity system with two surface water sources in the Coast Range Mountains, a Water Treatment Plant, 10 miles of transmission lines, 4 service reservoirs, and the 90 miles of distribution system.
Haskins Creek Water Treatment Plant is located in a remote/rural area approximately 10 miles west of Carlton, Oregon on Haskins Creek Road. The Water Treatment Plant is a conventional dual-media filter plant that uses chlorine gas as the disinfectant. This is the only place chlorine gas is used in
the system. The average amount of chlorine gas used in one day is less than 100 pounds. A one ton cylinder provides the chlorine. Another one ton tank is in standby ready for an automatic switch over should the primary tank empty. Only two tanks are connected to the chlorine system at any time. In addition, there is room to store another four one ton tanks of chlorine at this facility. Six is the maximum number of one ton tanks this facility can accommodate.
This facility is normally manned 8 hours a day six days a week. Qualified operators spend about an hour a day checking this facility on the days when an operator is not present for an 8-hour shift. In addition a computer control system has been installed. This electronic system continually monitors and records water quality and the treatment processes 24 hours a day. This electronic monitoring includes chlorine levels of the water as well as chlorine leak detector. Should a problem arise, the system will automatically
call out qualified operators to respond.
This facility has been in operation since 1977. Written procedures for handling chlorine tanks were developed and have been in use for years. In addition, we have developed policies and procedures that meet the requirements of Risk Management Regulations and Process Safety Management Regulations. These written plans have been coordinated with McMinnville Fire Department, the Yamhill County Emergency Services and the City of McMinnville. All operators are aware of these procedures and have been trained to properly handle these tanks and any leak that might occur. This training includes use of personal protective equipment as well as special tools required for these chlorine tanks.
The chlorine equipment is regularly maintained according to manufacturer's recommendations with only industry standard replacement parts used. System upgrades have been performed to enhance safety, reliability and control.
This facility has never h
ad a reportable accidental chlorine release. In the last ten years, there have been only two small chlorine releases. These releases were under the minimum requirements so they were not reportable accidental releases. These minor releases occurred when installing a new tank to the automatic feed system. Operators immediately took corrective action and resolved the problems. There were no offsite injuries or evacuations and there were also no onsite injuries with either of these two minor releases.
The offsite consequence analysis includes consideration of two chlorine release scenarios, identified as "worse case release" and "alternate release" scenarios. The modeling software used was the EPA's RMP Comp for both scenarios. The "worst case release" scenario followed conditions predefined by the EPA, namely a release of one entire ton container in 10 minutes. Even though this scenario is highly unlikely, it provides useful data for planning purposes. The software determined the
"toxic endpoint" as 3 miles in all directions from the water treatment plant. Using US Census Bureau data, the estimated residential population affected is 915, however, there are no private residences near the plant. Due to our control and monitoring systems, safe operations and procedures, this plant has never had a release that has affected any offsite residences.
The "alternate release" scenario was selected because it considers a valve leak that has occurred with one of our minor releases. Although the release considered in this alternate scenario is much greater than any release we have had, it provides data for planning purposes. The chlorine is contained in an enclosed room and this was used as a mitigation system in calculating the "toxic endpoint". This scenario assumes a release of 20 pounds per minute for 15 minutes with a calculated "toxic endpoint" of 0.2 miles and the calculated estimated population affected is 4. However, there are no private residences within t
his distance from the plant.
An emergency response procedure has been developed and reviewed by Yamhill County Emergency Services, McMinnville Fire Department and all members of the McMinnville Water & Light chlorine leak response team. The chlorine leak alarm is tested every week. The leak response team receives training and drills using the chlorine leak repair kit and self contained breathing apparatus. Everyone on the response team is knowledgeable of the written procedures and policies.
McMinnville Water & Light is committed to safety and considers this plan an excellent prevention plan for chlorine releases. All employees on the chlorine leak response team have participated in the development of this plan and suggestions for improving safety are encouraged. This plan will help ensure that Haskins Creek Water Treatment Plant's excellent safety record continues.