KRMA Regional Treatment Facility - Executive Summary |
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The Kankakee River Metropolitan Agency (KRMA) is a Joint Municipal Sewage Treatment Agency which has responsibility for administering the operation of a regional wastewater treatment facility. In addition to the effluent discharge and sludge disposal permits issued to KRMA by the USEPA , applicable Air pollution control permits and employee safety requirements also must be met. As a municipal entity in Illinois , KRMA is subject to rules set forth by the Illinois Department of Labor regarding safety training and safe work practices. The City of Kankakee Municipal Utility operates and maintains the treatment facility which serves the Villages of Bourbonnais , Bradley , and Aroma Park and the City of Kankakee under an intergovernmental agreement with KRMA. The safety policies and procedures developed by the Kankakee Municipal Utility for its personnel were adopted by KRMA as part of the contractual agreement for O&M services. As indicated above , the primary activity at the site is w astewater treatment services for the four municipal entities which are represented by KRMA. The process utilized for treatment involves screening and degritting , primary clarification , anaerobic digestion of solids , conventional activated sludge biological treatment , aeration , secondary clarification , disinfection with chlorine gas , and dechlorination with sodium bisulfide prior to discharge. The disinfection process is only operated from May 1 through October 31 each year as allowed by the operating permit. The chlorine used for disinfection is in the form of liquified gas contained in one ton cylinders. The plant may have as many as nine (9) ton containers onsite during the chlorination season which would be a total of 18,000 lbs. of the regulated chemical subject to the 112(r) regulations. Chlorine is the only regulated substance at the plant above the threshold amounts established by the RMP regulations. The facility reduces the risk of a chemical (chlorine gas ) rele ase by combining adequate ton cylinder storage and handling equipment , properly designed chlorine regulators and vacuum feed equipment , suitable connectors , and well thought out policies and procedures for operating the chlorination process. There are specific procedures to be followed whenever connecting or disconnecting ton cylinders and to check for leaks after a new cylinder is put online. Normal operation would involve having four (4) tons "in process". Two would be hooked up and in service with the other two hooked up but in standby mode. These tons would be put into service during high flow events or whenever additional chlorine feed is needed. The system involves removal of chlorine gas through a regulator under vacuum created by feed pumps which mix the chlorine gas with the treated effluent in a concrete tank. The chlorine feed rate is controlled electronically to maintain a set point. The chlorine regulators incorporate a switch-over feature which will automaticall y begin to draw from the second cylinder online when the first one is emptied. However , as the system operates on a vacuum principle , the regulators are designed to shut down whenever the suction is lost. This is an important safety feature of the system which significantly reduces the volume of chlorine which would be released due to a break in the chlorine delivery lines or if the chlorine feed pumps should fail. Our chlorine control room which contains the feed control equipment is equipped with a chlorine leak alarm system and incorporates an automatic ventilation fan which is activated whenever the entry door is opened. These two features will protect personnel by generating an alarm if a chlorine leak is detected and assures adequate fresh air is present in the control room whenever an operator is in the room performing necessary tasks for operating the system. The chlorine cylinders are stored on trunnions located below an electric hoist system designed for the purpose of unloading , loading , and positioning ton containers as needed to efficiently operate the disinfection process. All chlorine deliveries by our supplier are made utilizing flatbed trucks suitable for accepting empty ton cylinders and delivery of full containers. Typically , approximately 35 tons of chlorine are used per year. This involves 4 - 5 deliveries each season. The ton cylinders provided with protective covers over the valves which are only removed immediately before the gas regulators are installed prior to use. These protective covers remain in place for all ton containers which are not "in process". The ton containers are maintained and refilled by the supplier in accordance with applicable rules , regulations , and industry practices. The chlorine supplier provides annual chlorine safety training for our personnel as well as for Kankakee Fire Department personnel. The 112(r) regulations require that the RMP discuss both a "Worst Case Scenario" and an "Alternate Ca se Scenario". The "Worst Case" incident involves release of all "in process" quantities of the regulated substance in 10 minutes. It is further assumed that any active or passive mitigation equipment or processes are inoperative during a "Worst Case" event. For the KRMA facility , such an event would involve the release of 8,000 lbs. (the contents of the four online ton cylinders) of chlorine gas in ten minutes. Based on the "Worst Case Release" tables included in the USEPA RMP Guidance for Wastewater Treatment Plants (40CFR Part 68) , such a release could impact an area within a 2.7 mile radius from the plant. The Kankakee County planning office estimates the potential effected population in this area to be 43,000 people based on census tracts. This impact area also includes several schools , nursing homes , shopping areas , and the area's two hospitals. The selected "Alternative Scenario" involves chlorine gas released through a one - quarter inch diameter hole in a single ton cylinder. Such a release would occur with the loss of a fusible plug due to excessive heat / pressure. The fusible plug is designed to release chlorine gas in a controlled way in high temperature or pressure situations in order to avoid catastrophic releases. The chart supplied in the USEPA guidance document defines an impact area radius of 0.1 mile for a release of this type. If the size of the opening in the ton cylinder is increased up to an inch in diameter ( as in a broken valve line ) the radius of impact increases to 0.2 mile and there is potential for "offsite impact" involving 29 nearby residences with an estimated 116 occupants. It should be noted that there are mitigative circumstances which would reduce the likelihood of offsite consequences even with a one inch leak source. The 29 homes are all located at higher elevation than the chlorine storage area and there is an area of lower elevation between the homes and the chlorine storage area. As a heavier than air gas , any chlorine released would tend to stay close to the ground and collect in low spots. This could help contain the release on the plant grounds and delay its dispersion. Another important factor is the wind direction. All of the homes potentially impacted are located to the east and north east of the chlorine storage site. If the wind direction during a release event is not from the west or south west , the residential area could escape any impact from a release. The impact radius charts do not take into consideration how the release rate is effected by temperature and pressure changes. As the gas leaks , the evaporation will cause the liquid gas to cool which will reduce the gas pressure. The reduction in both temperature and pressure will cause the release rate to decrease. There have been no chlorine gas releases at the facility during the past five (5) year period. In general , the KRMA facility has an outstanding safety record having completed 424 days without a lost time accident as of March 31 , 1999. There were no employee injuries of any kind for the entire year in 1998. The plan for response to a chlorine emergency involves contacting the Kankakee Fire Department to request their assistance , notifying and determining the location and condition of all plant employees and if necessary evacuating plant personnel to a safe location. The plant personnel are not certified to use air packs and would only assist the Kankakee Fire personnel in resolving the chlorine emergency. The fire department personnel are trained in the use of the Type "B" Ton Cylinder repair kit and would respond to and accomplish the required leak repair. Any offsite notification and or evacuation if necessary , would be in accordance with the Countywide Emergency Response Plan . |