Robert A. Duff Water Treatment Plant - Executive Summary |
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The Robert A. Duff Water Treatment Plant is one of two drinking water treatment facilities owned and operated by Medford Water Commission. The plant is located at 8301 Table Rock Road near White City, Oregon and is used to supplement the Big Butte Springs supply, operating only as needed about 6 months of the year from May to October. Together, the two sources serve nearly 95,000 persons in Medford and surrounding communities of Central Point, Phoenix, Jacksonville, Eagle Point and White City. The Robert A. Duff Water Treatment Plant uses the conventional treatment processes of coagulation, filtration and disinfection to purify drinking water from the Rogue River. Continuous disinfection is a critical process in drinking water treatment to ensure public health and Chlorine is used as the primary disinfectant to achieve that objective. Gas chlorination has been practiced without incident at this plant since 1968. The current design and construction standards for chlorination s ystems exceed those under which the plant was originally constructed. A major chlorination system upgrade occurred in 1999 to include state-of-the-art process equipment and controls. The Robert A. Duff Water Treatment Plant facility plan addresses further upgrades, including a gas scrubber. This improvement is currently scheduled for construction during the 2000-2001 budget year. Chlorine is transported to the site in one-ton containers by truck. Containers are off-loaded and handled at the facility with a monorail hoist. Chlorine is stored in up to 4 one-ton containers at the facility. Gas phase chlorine is withdrawn with vacuum from one of three containers connected to the plant chlorine feed system. Pressurized chlorine gas is reduced to vacuum as it exits the on-line container, passes through the chlorinator and is injected into plant process water. As the on-line chlorine supply is exhausted, containers automatically switch over to standby containers. Leak detecti on and alarm systems are included. The plant has developed a comprehensive prevention program designed to minimize the risks associated with Chlorine processes. The prevention program components include a systematic process hazard analysis, strict operation and maintenance procedures, and training. The Risk Management Plan has evaluated worst-case and alternative release (more realistic) scenarios to more fully understand the potential off-site consequences of an accidental release of Chlorine. The worst-case release scenario simulated a full container release within 10 minutes. Building containment would slow the release to open atmosphere to 110# per minute, resulting in a distance to the toxic endpoint, 3 PPM for Chlorine, of 2.2 miles. A number of public and environmental receptors would be affected within this radius. The alternative release scenario modeled a container valve leak inside the facility. With the building containment the affected radius was deter mined to be 0.2 miles and would encompass the Tou-velle State park entrance area, Table Rock Road and one residence. An emergency action plan is also in place protect workers and the public in the unlikely event of an accidental release of Chlorine. This plan encompasses a wide range of response actions depending upon the severity of the release situation. At atmospheric Chlorine concentrations below IDLH, Medford Water Commission personnel will react to contain or repair minor leaks. A significant release that may result in Chlorine concentrations above the IDLH level, the action plan would then involve Jackson County Fire District #3 and ultimately the Southern Oregon Regional Haz-mat Team #8. The Board of Water Commissioners, management and plant operations staff are confident the policies and procedures in place allow for the safe operation of Chlorine disinfection processes at its' treatment facilities. Further information may be obtained from the Water Commission off ice located at 200 S. Ivy Street, Medford, OR 97501 |