Hansen Water Treatment Plant - Executive Summary |
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Introduction Water District No. 1 of Johnson County operates a water treatment plant which draws water from both the Missouri and Kansas Rivers. The Hansen Water Treatment Plant consists of Facility No. 1, which is a 55 million gallon per day, lime-softening plant; and Facility No. 2, which is a 110 million gallon per day, lime-softening plant. Facility No.2 contains two separate chemical process areas. In addition to the plant, there are two intake and presedimentation facilities, one at the Missouri River and one at the Kansas River. These facilities will be covered in three separate Risk Management Plans. One plan will cover the facilities at the Hansen Water Treatment Plant, and there will be a plan for each of the intake facilities. This Risk Management Plan (RMP) covers the Section 112r regulated substances maintained at the Hansen Water Treatment Plant, which will be referred to herein as the Plant. Plant Description The Plant maintains two regulated substance on site: c hlorine and aqueous ammonia. Chlorine storage is 72,000 pounds, which exceeds the RMP threshold quantity of 2,500 pounds. Ammonia storage is 144,300 pounds, which exceeds the RMP threshold quantity of 20,000 pounds. The storage and management of both chlorine and ammonia are addressed in this RMP. The Plant is located at 7601 Holliday Drive, Kansas City, Kansas, which is an urban area. The Worst Case Release Scenario The worst case release scenario for the Plant was calculated as the release of the largest container of either chemical in accordance with the definition provided in the Environmental Protection Agency guidance for RMP development. A separate worst case scenario was analyzed for each of the chemicals, and an off-site consequences analysis was performed on the worst of the two. Passive control systems can be considered for the worst-case release, such as the containment provided by a building. The ammonia tanks are stored outside, however, so there are no passive controls for a worst case ammonia release. The conditions of the scenario, such as release time and weather status are those provided in the EPA Off-Site Consequence Analysis Guidance. The area of potential impact was determined using RMP*Comp, modeling software developed by the EPA. The results of the Off-Site Consequence Analysis indicated that the chlorine would travel approximately 0.9 miles under the specified weather conditions before dispersing in the atmosphere to the specified end point concentration. The ammonia would travel approximately only 0.4 miles before dispersing to the specified end point concentration. The worst case release area is a 0.9-mile radius circle around the plant. Within this area, an estimated 1200 persons could potentially be affected. A map of the area and a list of the types of receptors in the potential impact area are provided in the Off-Site Impact Analysis Section. The list of potential receptors includes: 7 one school 7 one recreation are a 7 one industrial area This type of rapid release would only occur if the chlorine cylinder valve was broken off, or the cylinder was breached. The likelihood of such an incident occurring is minimal. Alternative Release Scenario The alternative release scenario is, by definition, a more likely release scenario than the worst case. Engineered controls, such as the leak detection system and alarm, and scrubbers installed at the site are considered in the analysis. The type of system failure selected for the chlorine alternative release was the loss of chlorine due to a break in the flexible tubing leading from the cylinder to the vacuum regulator. The chlorine would leak from a 3/8" opening. The leak would continue until the chlorine detection alarm sounded and the valve on the cylinder could be closed. Scrubbers would remove 99.999% of the chlorine from the air before it leaked outside the building. Because chlorine would have leaked into the chlorine room, response would be made by HazMat Response according to their procedures for a toxic chemical release. The time for the response was estimated at 60 minutes. Once on site, the response personnel would enter the room in protective clothing and close the valve on the leaking cylinder. The type of system failure selected for the ammonia alternative release was the loss of ammonia due to a break in the pipe leading from the tank into the building. The ammonia would leak from a >-inch opening. The leak would continue until the next inspection by the operator at which time the valve on the tank could be closed. There are no passive controls for a leak in this system. For an extensive ammonia leak, response would be made by HazMat Response according to their procedures for a toxic chemical release. Once on site, the response personnel would approach the area of the spill in protective clothing and close the valve on the leaking tank. The time for the response was estimated at 2 hours. There is no d etection system for ammonia, so the leak would continue until the plant staff made an inspection of the feed systems and recognized a drop in flow. Inspections are conducted every two hours. The results of the Off-Site Consequence Analysis using RMP*Comp, indicated that the chlorine would travel less than 0.1 miles under the specified weather conditions in order to disperse in the atmosphere to the specified end point concentration. Within that radius of the Plant, an estimated 65 persons could potentially be affected. The ammonia would also travel less than 0.1 miles before dispersing to the specified end point concentration. This would also potentially affect approximately 65 persons. Maps of the area and a list of the types of receptors in the potential impact areas are provided in the Off-Site Impact Analysis Section. Process Hazard Assessment A process hazard assessment was performed on the chlorine and ammonia systems beginning with the unloading of the container and endi ng with each chemical in solution. A checklist and a modified "What if" analysis were used. In the checklist analysis, general questions regarding the storage and use areas, as well as protocols associated with the management of the chlorine and ammonia systems, were answered. A copy of that checklist is included in this plan. Following the checklist, each valve, line, and piece of equipment in each system was assessed from the cylinder or tank to point of chemical injection using a system flow diagram. The valves and other points in the system where the chemical could be released are numbered on the flow diagram. The assessment is formatted in accordance with those numbers. Compliance with code requirements, potential failures, maintenance and inspection concerns, and standard operating procedures were reviewed for each point in the system. Comments are summarized in the Process Hazard Assessment section. Prevention System The Plant has an operation, maintenance and inspection system designed to review each element of the chlorine and ammonia systems routinely. There are Operation and Maintenance manuals for each major piece of equipment, and personnel receive significant training before being allowed to work on the systems. As each cylinder is changed, the valves and flexible whip connection of the chlorine system are tested for leaks. There are standard operating procedures (SOPs) for startup, shutdown, normal operation, and emergency operation of both systems. The SOPs are written and posted in the appropriate areas. Personnel are trained routinely on safety concerns and general operation procedures as well as emergency procedures. The chlorine system is equipped with chlorine detectors and alarms that indicate leaks. Emergency Response Plan Any response requiring entry in a dangerous atmosphere requiring Level A personal protection or use of a chlorine repair kit is to be managed by Haz-Mat Response Inc., an emergency response company located in the Kansas City area. A complete copy of the Emergency Response Plan (Emergency Action Plan) is included. Accident History The Plant has had no chlorine or ammonia releases in the past five years. |