East Grand Forks Water Treatment Plant - Executive Summary |
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WATER SYSTEM DESCRIPTION Source Water Raw water for the East Grand Forks Treatment Plant is drawn through two intake lines located in the Red Lake River to a wet well. Three pumps, two with capacities of 1400 gallons per minute (gpm) and one with a capacity of 2800 gpm, deliver the raw water from the wet well through a transmission line to the water treatment plant. Water qualities for the Red Lake River under extreme conditions are shown below: Red Lake River Turbidity 6-900 TOC (mg/l) 9-25 Temperature 0.5-25.0 pH 7.6-8.3 Hardness (mg/l as CaCO3) 130-440 The high turbidity and hardness of the source force the plant to use aluminum sulfate (alum) coagulation, lime/soda ash softening, and rapid-rate dual medi a filtration year round in order to produce a suitable quality of drinking water. Treatment Plant The East Grand Forks Water Treatment Plant is a rapid rate, dual media filtration plant with solids enhanced pretreatment, solids enhanced lime/soda ash softening, fluoridation, stabilization, chlorination, and chloramine disinfection. The East Grand Forks Water Treatment Plant has a maximum treatment capacity of 2780 gpm which corresponds to approximately 4 million gallons per day (MGD). To meet consumer demands, the East Grand Forks Water Treatment Plant at times operates its maximum treatment capacity during the summer and winter for an operating period of 16 to 24 hours per day. Treatment at the plant begins in the influent line to the pretreatment basin, where alum is added as a coagulant to help remove turbidity and color from the raw water, potassium permanganate or carbon is added for taste and odor control and a cationic polymer is added seasonally to aid in the settling proc ess. Following pretreatment, the water flows to the softening basins. In the softening basins, lime and soda ash are added to remove the hardness, with sodium aluminate and/or a cationic polymer added as coagulant aids. The pH of the water after softening ranges between 10.5 and 11.0 following softening, is lowered to approximately 9.0 with the addition of carbon dioxide in the recarbonation basins. Chlorine is injected into the filter influent line ahead of filtration. At this point in the treatment process, poly phosphate is also added to stabilize the water (limited corrosion inhibition is also provided by the poly phosphate) and fluoride is added for dental health purposes. Filtration of the softened and recarbonated water is performed in two double bay, dual media filters. The media in the filters consists of 12 inches of anthracite, 12 inches of sand, and 16 inches of various grades of gravel below the sand and anthracite for support. The filters at the East Grand Forks W ater Treatment Plant are loaded at approximately 2.0 gal/min/ft2. The filters are backwashed on a regular basis and the filter backwash water is held in a storage basin before being pumped to the sanitary sewer. Storage at the East Grand Forks Water Treatment Plant consists of a 129,000 gallon clearwell and a 1,000,000 gallon finished water reservoir (FWR). Water is pumped, using transfer pumps, from the clearwell to the FWR by two 1400 gpm and one 2800 gpm centrifugal pumps. The finished water reservoir is served by two 2800 gpm and one 1400 gpm high service pumps. Treated water leaves the East Grand Forks Water Treatment Plant through a series of transmission lines ranging in size from 12 to 18-inches in diameter depending on service area and flow required. The City of East Grand Forks currently utilizes three elevated water towers, two 500,000 gallon towers, and one 100,000 gallon tower. The 100,000 gallon tower is used only in the summer months to fulfill high water demand. In addition to the elevated storage, the city also utilizes a 2 million gallon (MG) underground storage reservoir within the distribution system. Letter from Minnesota Municipal Utilities Association..... The general accidental release prevention program and chemical specific prevention steps Our facility complies with several portions of the OSHA regulations relating to release prevention. The Hazard Communication Standard (1910.1200) and Minnesota Statutes (Chapter 5206), also known as "Employee Right to Know" require specific training in regards to working with hazardous chemicals. These regulations also require the City of East Grand Forks to transmit the relevant information concerning the hazards of chemicals to employees. OSHA 1910.176 - Material Handling and Storage requirements are in place that create awareness of the chemicals and their associated hazards. OSHA 1910.119 - Process Safety Management requirements are in the development stage. Minnesota Statutes 182. 653 - A Workplace Accident and Injury Reduction. The City of East Grand Forks, by law, must establish a written workplace accident and injury reduction program that promotes safe and healthful working condition. This program descries: 1.) how managers, supervisors, and employees are responsible for implementing the program and how continued participation of management will be established, measured, and maintained: 2.) the methods used to identify, analyze, and control new or existing hazards, conditions, and operations; 3.) how the plan will be communicated to all affected employees so that they are informed of work related hazards and controls; 4.) how workplace accidents will be investigated and corrective action implemented; and 5.) how safe work practices and rules will be enforced. The employer must then conduct and document a review of the workplace accident and injury reduction program at least annually and document how procedures set forth in the program are met. Plann ed changes to improve safety The City of East Grand Forks contracts with the Minnesota Municipal Utilities Association (MMUA) for safety compliance management services. This service provides us with safety training, job hazard analysis, procedures development, and other relevant compliance services. Safety training occurs on a monthly basis, with topics that include Hazard Communication and AWAIR. The institution of this RMP will give us cause to institute additional training regarding the plan and working with the chemical hazards. Portions of this training will be arranged with MMUA. Other entities will also continue to provide specific training on the chemical hazard. The development of the safety program will undoubtedly improve the overall safety of the plant. Recieved from: Joe Schmidt Regional Safety Coordinator Minnesota Municipal Utilities Association 12805 Highway 55 Suite 212 Plymouth, MN 55441-3859 612-551-1230 In case of a worst case and alternative case release scenario of chlorine, a sector of the area involved due to wind direction and speed, atmospheric stability and also topography could be effected. Chlorine is a regulated substance and must be reported to the EPA when exceeding 2500 pounds at the facility's location. As in this case, the East Grand Forks Water Treatment Plant. Model used to determine areas effected in a accidental release of chlorine is the ALOHA model (Area Locations of Hazardous Atmospheres) The distance and concentration of a accidental chlorine leak is mapped out. Refer to map (s) included and submitted to EPA as part of the Risk Management Plan. Preventive measures from a possible worst case and alternative case release of chlorine have been addressed. East Grand Forks Water Treatment Plant Chlorine Feed System was converted from a pressure feed system to a vacuum system. This update was completed in 1988. Also, personnel routinely monitor for faulty feed equipment and chlorine leaks. Training is provided . This facility also has a 1 (one) ton chlorine tank repair kit that is available for emergency personnel. Presently (1999) a chlorine scrubber is being installed to handle a major chlorine leak, if such an event would occur. This project will be completed early fall of this year. In the past 5 (five) years, East Grand Forks Water Treatment Plant personnel have had no accidental releases of chlorine, or injuries due to exposure of chlorine. This is a track record that this utility hopefully continues to keep in place. Letter from East Grand Forks Fire Department...... Haz-mat Response Water & Light 1.Call comes in on 911 to notify Fire Department of Haz-Mat incident. 2.Identify product and area affected by incident. 3.Notify Police Department, Sheriff, to help evacuate. 4.Call Minnesota Duty Officer to notify of incident and dispatch state haz-mat team if necessary. Recieved 4-2-99 from: East Grand Forks Fire Department 415 4th Street NW East Grand Forks, MN 56721 21 8-773-2403 |