The Connector - Summer 2008 - (Page 19)

RWAU Summer 2008 Tank Cleaning 101 Terry Smith, Southern Circuit Rider s I write this, it’s snowing while at the same time the sun is shining. I guess this is Mother Nature’s way of easing us into summer. And with the summer weather comes the increased demand for water. I’ve always felt that summertime for water departments is equivalent to Christmas time for toy stores—too much to do, too little time! Among the various chores that are best done when the weather is mild and conditions are best is to inspect, evaluate and, if needed, clean your water tank or tanks as the case may be. At present there isn’t a rule requiring how often tanks should be cleaned, and it would be difficult to write one, since factors can be very different between the various systems. Some systems may have a problem with sand from their wells, requiring that the tank be cleaned on a regular basis. Others may have only a spring source that delivers pristine water year round, and thus seldom needs to be cleaned. Steel tanks should be inspected yearly to see how the coating is holding up, while concrete tanks, with the absence of coating, may not need to be inspected as often. It therefore falls to each system and its operators to decide how often this needs to be done. As with most operations, when dealing with drinking water there are regulations written to outline the correct procedures when cleaning your tank as well. ANSI/AWWA C652-02 spells out the correct ways to have tanks cleaned or inspected, whether this is done by underwater divers or by draining the tank and manually inspecting/ cleaning the tank. There are quite a few companies that offer tank cleaning and inspection services—and several of them are here in Utah. This is normally accomplished by having a diver first enter the tank when it is full to ascertain the condition of the tank and the amount of material that needs to be removed. Regulations pertaining to this operation include but are not limited to the following: A • All equipment and clothing to be used for inspection/cleaning of potable water storage facilities shall be dedicated for that purpose only. • Both SCUBA (self-contained underwater breathing apparatus) and externally supplied air methods are acceptable air sources. • All equipment exposed to the water shall be suitable for disinfection. Divers shall be completely encapsulated with no bare skin exposed. Diving clothing shall be of the drysuit type and shall be in good condition. The diver and the clothing shall be disinfected after the diver is suited up and on top of the tank. All equipment and clothing shall be stored in a manner that prevents both chemical and bacteriological contamination. • There shall be no contact of the mouth or head with the water during any underwater operations. The head shall be fully encapsulated by one or any combination of the following: helmet or dry suit hood with full-face mask. • Divers shall have communication in accordance with federal, state, provincial and local regulations. • All equipment that will enter the water storage facility must be disinfected immediately prior to entry into the potable water reservoir. Any equipment making contact with the tank roof must be disinfected again prior to entry into the water. The method of equipment disinfection can be submersion in, spraying with, or sponging with disinfectant solution as defined in ANSI/AWWA C652-02 sec. 4.3.2. In addition to following the correct procedures, divers also need to be qualified. Some acceptable qualifications are listed in the standard as: • 2nd Class US Navy Diver Training • ANSI/ACDE 01 Commercial Diver Certification 19 • ADC Commercial Certification • All certifications shall be accompanied by documentation showing experience with direct tank inspection and cleaning experience. If you decide to go the route of hiring a contractor to inspect and/or clean your tank, ask for some references and carefully go over what you expect to receive from the job and what the costs are expected to be. Underwater tank cleaning can be fairly expensive, but if you have a tank that is difficult (or impossible) to take offline for the period of time necessary to manually inspect/ clean it, it may be worth the cost. But what if you can take the tank offline, and would like to inspect it, and if necessary, clean it? I’ve found that on smaller tanks, a lot of inspection can be accomplished right from the entry hatch on top of the tank. By draining the water down to around 1/3 of the tank’s capacity and utilizing a mirror that is sized around a foot square, you can reflect a lot of light into the tank on a sunny day. This will allow you to inspect the walls and floor well enough to get a good idea of how things are holding up. If all looks good, you may not need to do any more. But, if you can see rust spots appearing and/or the floor looks as though it may have a build up of sand on it, it might be a good idea to set up a time to drain the tank for a closer inspection. Also, if you feel like the coating may need to be repaired or replaced, it might be a good idea to have a contractor onsite when you drain the The Connector

Table of Contents Feed for the Digital Edition of The Connector - Summer 2008

The Connector - Summer 2008 Contents President's Message Executive Director's Comments Letters From Readers Legislative Update Rural Water News The Basics Shannon Rasmussen Sanitary Surveys - What to Expect: Part 1 Chuck Jeffs Tank Cleaning 101 Terry Smith Where in Utah?

The Connector - Summer 2008

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