The Connector - Summer 2008 - (Page 20)

Summer 2008 tank so that he can inspect it and give you an idea what you might be looking at cost-wise to either repair, or in worse case, sand-blast the old coating off and replace it with new. So, let’s say you’ve inspected the tank from the top; the coating looks good, but you can see that the floor could stand a little maintenance in the way of cleaning. Taking the tank offline doesn’t pose a real problem—you schedule a day, let the tank level get as low as you can beforehand to avoid wasting a lot of water and time, then start the draining process. Make sure you start the draining process early enough in the day that you have plenty of time to complete the tank cleaning before evening arrives. If you end up standing around burning daylight for half a day waiting for the water to drain, it can get really tough to see inside the tank when the sun gets low on the horizon. My advice would be to start draining early in the morning— say around 5:00 am. It always seems to take longer than you plan on! Once the tank is drained, it’s time to get started. A lot of times, by allowing water to run from the inlet across the tank floor to the drain, you can simply sweep the sand to the drain using sturdy shop style push brooms. Sometimes you may find a “volcano” of sand around the inlet pipe that will necessitate some shoveling into buckets and carrying it out to the inspection hatch to be dumped. I’ve also seen times when the sand, while only an inch or two thick, was so compacted that trying to sweep it off the floor was about as successful as trying to remove a concrete driveway in the same manner. If this is the case, you may end up shoveling all of it out! If so, depending on the size of tank and the amount of help you’ve conjured up, you may end up extending this job more than one day. So, here you are at the end of the day surveying your tank, which with a lot of effort and elbow grease is now sparkling clean. One last task remains, however, before you can put it back online, and that is the process of disinfection. Once again, there are a set of rules that we can follow to ensure that this is done correctly. To disinfect the tank, we have three options: 1. By adding enough chlorine to the water to ensure that there will be at least 10 mg/l (parts per million) free chlorine at the end of the treatment period, you can fill the tank to overflow, then either drain it back out, or blend it with the incoming water until the chlorine residual is reduced to the point that it can safely be turned into the distribution system. Gas, liquid or powder can be used, and the treatment period depends on how you apply the chlorine. If you feed the chlorine gradually into RWAU the water while the tank is filling, then you can drain the tank after a contact time of six hours. If, however, you pour the chlorine into the water at the beginning, you must apply a contact time of 24 hours before draining the tank to allow the chlorine to thoroughly mix with the water. Also, consideration may need to be given to de-chlorinating the water from the drain pipe should there be a sensitive area nearby. After you have received satisfactory results from bacteria samples (bac-t’s) you have taken from the tank, you can turn the water into the distribution system. 2. Fill the tank to approximately 5% of total capacity. Then add enough chlorine to make a solution of 50 mg/l. Allow this to stand for at least 6 hours, and then fill the tank to overflowing. After the tank is full, flush the drain pipe to remove the highly chlorinated water. Once again, you’ll need satisfactory bac-t’s before turning the tank into the distribution system. 3. And finally, (my method of choice) apply a solution of 200 mg/l available chlorine directly to all surfaces of the storage facility that come into contact with the water. This can be done with either brushes (remember those push brooms you used earlier?), or with spray equipment. Contact time needs to be at least 30 minutes, so you’ll need to brush or spray it several times (If available, and you can get them to do it, your local fire department’s brush truck is perfect for applying the chlorine solution). Once you have done this, you can turn the water in to begin filling the tank. Finally, before putting the tank back online, remember to flush the drain pipe to remove the chlorine, and once again you’ll need those satisfactory bac-t samples. So, there’s the rundown of cleaning tanks 101—nothing to be afraid of. And if after reading this, you decide to tackle that cylinder shaped monster of yours, feel free to give your local Rural Water folks a call for help. We’ll be glad to lend a hand! I’ll see you in the spring (now where did I store that snow shovel…) BUY OFF STATE CONTRACT! www.lakecitytrucks.com AVOID GOING TO BID! STOCK UNITS ON ORDER! Ryan Hanks The Connector 369621_LakeCityTrucks.indd 1 Ofﬁce: 801-972-7101 Mobile: 801-577-5379 hanks@lakecityint.com 964 South 3800 West Salt Lake City, UT 84104 20 3/12/08 7:12:17 PM http://www.lakecitytrucks.com http://www.lakecitytrucks.com

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

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.