East Section Reclamation Plant - Executive Summary

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King County East Section Reclamation Plant 
Executive Summary 
 
 
This summary describes the Risk Management Plan for the King County East Section Reclamation Plant, a publicly owned wastewater treatment facility.  The plan was prepared to meet federal EPA requirements stated in Section 112r of the Clean Air Act and 40 CFR Part 68 which is commonly known as the Risk Management Program.  It describes the chemical systems that fall within this regulation, and explains King County's policy and procedures for preventing chemical accidents and preparing to respond to accidents in order to protect our employees, community and environment. 
 
Background 
The East Section Reclamation Plant at Renton is a wastewater treatment facility located in Renton, Washington.  It is owned and operated by the King County Wastewater Treatment Division.  The plant was originally built by Metro (Municipality of Metropolitan Seattle), began operating in 1965, and became part of King County in 1996 when Metro and Kin 
g County were merged.  The plant serves 600,000 residents within a 140-square mile service area that is located on the east side of Lake Washington extending from South Snohomish County to South King County.  
 
The East Section Reclamation Plant is charged with transporting and treating the area's wastewater in order to protect the public health of the community and to preserve the water quality of Lake Washington and Puget Sound.  It accomplishes this by collecting the area's wastewater, removing pollutants contained in it, and disinfecting the clarified wastewater prior to discharge into Puget Sound. 
 
Wastewater Treatment Process and Chemicals 
Wastewater collected from the service area enters the East Section Reclamation Plant and is progressively cleaned by going through three stages of treatment.  The first two stages, called preliminary treatment and primary treatment, are physical processes that remove floating material, heavy solid material such as sand, and about two-thirds of t 
he organic material.  The wastewater then moves on to secondary treatment, a biological process that uses naturally occurring microorganisms to remove organic pollutants from the wastewater.  After this biological step, the wastewater is clarified, disinfected, and discharged.  The entire treatment process is designed and operated to meet EPA's water quality requirements for discharge into Puget Sound. 
 
Solid materials removed from the primary and secondary treatment processes are transferred into an enclosed tank and combined with another set of naturally occurring microorganisms that break down or digest the solid matter.  The digestion process produces a by-product called "digester gas."  Digester gas is mostly composed of methane, a gas similar to natural gas. 
 
Two chemicals at this treatment plant are listed in the Risk Management Program.  The first chemical, chlorine, is used to disinfect the wastewater prior to discharging it into Puget Sound.  Chlorine is also occasionally use 
d in small amounts to control odors generated at the treatment plant.  Methane, a component of digester gas, is the second chemical.  Methane is collected from the digestion process, cleaned, and sold to a commercial natural gas company for distribution and use in energy production. 
 
The East Section Reclamation Plant is currently under construction to expand its capacity and improve its systems.  Construction improvements have included upgrading the chlorine, digester gas, and other systems at the plant with proven, state-of-the-art equipment. 
 
Risk Management Program 
The Risk Management Program requires that hypothetical worst-case and alternative release scenarios be prepared for each listed chemical.  The regulation defines the worst-case scenario as a series of worst-case circumstances that occur at the same time.  The worst-case scenario assumes that the following occurs simultaneously:  the entire quantity of the largest container in a system is quickly released;  weather condit 
ions are at its worst-case;  electronic control systems and active chemical scrubbing systems are not operating;  and response procedures are not used to prevent or minimize the release.  For the chlorine system, the worst-case scenario is considered to be the release of the entire contents of one 90-ton railcar within the chlorine building.  The liquid spill and vaporization release would be lessened or mitigated by the building enclosure.  This release could potentially reach areas outside the plant. 
 
The worst-case scenario is a hypothetical and virtually impossible chain of events.  Our chemical systems have multiple and redundant safety systems such as containment structures, control systems, neutralizing systems and emergency procedures to prevent or minimize the extent of accidents.  Further, the laws of physics would prevent such rapid evaporation and release rates. 
 
The alternative release scenario is also a hypothetical situation, though it is based on more realistic circumst 
ances where the nature of the accident is selected from analyzing the system, weather conditions are typical for the facility's location, and automatic control systems and safety systems operate as intended to minimize damage if there is an accident.  For the chlorine system, the alternative release scenario is considered to be a pipe break in the chlorine line which results in a leak of up to 350 pounds of chlorine.  This scenario also assumes that the chlorine building's active chlorine scrubber isn't operating, however, the chlorine building enclosure would mitigate the leak. This release could potentially reach areas outside the plant. 
 
The worst-case scenario for the digester gas process (a flammable mixture) is considered to involve a release and vapor cloud explosion of 8,500 pounds of methane, the maximum quantity of methane contained in the digester blend and storage tank.  This release could reach areas outside this facility.  An alternative release scenario for the digester  
gas process would involve a release of the same quantity of methane as a buoyant gas plume.  Ignition of the plume could also affect areas outside this facility. 
 
20 Years of Safety 
The East Section Reclamation Plant has been operating 24 hours a day, seven days a week since 1965.  It has had no reportable accidents in the past five years, and no major accidents of chlorine or digester gas in over 20 years of operation.  We are proud of this safety record and attribute it to a multi-pronged accident prevention approach which includes a well-designed facility, well-trained and knowledgeable employees, and a philosophy to continually improve our operations. 
 
King County's policy is to meet or exceed all regulations that apply to our wastewater treatment facilities;  this policy extends to the Risk Management Program.  Our systems are designed and operated according to regulations, industry standards, and sound engineering practices.  Multiple levels of protection are designed into our sy 
stems to prevent accidents and minimize effects in case of an accident.  These layers of protection typically include a combination of the following:  equipment and piping that are designed with safety factors to safeguard against material failure;  monitoring and alarm systems to warn plant operators and automatically startup safety systems if there is a problem;  systems such as isolation valves, and eductors and scrubbers to neutralize chemical releases;  and containment structures such as a building or large sump to prevent releases from widely dispersing. 
 
At the East Section Reclamation Plant, the chlorine system is contained in an enclosed building specially constructed with an emergency sump, chlorine scrubber, alarms, and automatic control interlocks to contain and minimize the amount of chlorine that would be released in case of an accident. The chlorine scenarios described earlier assumed that the chlorine scrubber wasn't operational.  Under normal conditions, the chlorine s 
crubber is on standby and ready to operate at any time.  Any chlorine leak would cause the scrubber to start up and neutralize the leak so that it is unlikely that chlorine would be released into the environment.  The digester gas system has redundant sophisticated control systems and sensitive audio and visual gas detection alarms to notify plant operators if there is a gas leak.  The plant also has a scheduled preventive maintenance program, and our maintenance employees are trained and skilled to keep all equipment operating properly. 
 
The best way to assure safe operations is to have well-trained, knowledgeable employees.  All of our plant operators are licensed and certified by the State of Washington.  All other plant employees such as the maintenance, laboratory and process control staff are trained to perform their work in a safe manner.  Training and refresher classes are taught regularly to keep skills updated.  Employee safety is a top priority at the King County's treatment 
plants, and the plant's philosophy is to continually improve safety in operations.  All plant employees attend safety training classes and safety informational meetings, and a safety committee composed of employees meets monthly to review safety incidents and recommend safety improvements.  A chlorine cross-organizational task force manages a safety, training, operations and maintenance program specifically for the chlorine facility. 
 
Emergency Response Program 
To prepare for accidents, the East Section Reclamation Plant has an emergency response plan that has evolved from a successful existing program and is continually improved.  The treatment plant employees perform drills regularly to practice emergency response procedures, and use the knowledge gained during drills to improve the emergency response plan.  As part of our emergency response practices, operations personnel are continuously on duty and maintenance employees are regularly scheduled for on-call duty to respond in the e 
vent of a plant emergency. 
 
If there is an emergency involving the chlorine or digester gas systems, King County's policy is to notify the City of Renton Fire Department, King County Local Emergency Planning Committee, and King County Office of Emergency Management, and request that they respond to the emergency.  King County employees have practiced emergency drills with the City of Renton Fire Department Hazardous Materials Response Team, and have also conducted training and emergency drills with the City of Kent Fire Department and the City of Tukwila Fire Department. 
 
Commitment to Accident Prevention 
Accidents can happen at any time.  We are continually aware of this and work toward minimizing the potential for accidents by having a state-of-the-art, well-maintained facility, trained employees, an employee-based safety committee, a practiced emergency response plan, and an outlook to continually improve operations.  These practices assure safe operations so that the East Section R 
eclamation Plant can continue to protect our community's public health and our region's water quality. 
 
If there are any questions, please contact the King County Wastewater Treatment Division at 206-684-1280. 
King County East Section Reclamation Plant 
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