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(continued from page 11) <br />Subsequently, Kansas sued Nebraska over <br />similar issues on the Republican River basin. This has <br />resulted in the State of Nebraska changing its water <br />rights policies to require groundwater usage to be <br />included in an overall water resources approach. New <br />studies are looking at water use in the basin and may <br />result in reduction in use of groundwater so that ad- <br />equate river flows can be maintained. <br />There are existing issues being resolved by <br />court as well as cooperative efforts between Colorado <br />and Nebraska, Colorado and Wyoming, and Colorado <br />and New Mexico. This is notjust a Colorado issue, but <br />is building momentum across the country. Law suits <br />over who can use how much of what water supply <br />have been very evident in the water -rich East. While <br />these are generally surface water issues, they have <br />long term impacts on groundwater supplies through- <br />out the whole west, and will eventually do the same <br />in the rest of the country. <br />The demands of increasing population on a <br />limited quantity of water are resulting in increased <br />changes in both out life styles and in the way we <br />consider nature. Parts of the Arkansas Valley in Colo- <br />rado are being taken out of irrigated agriculture and <br />returned to barren ground. Parts of Nebraska are <br />facing the same issues in the Republican Valley. The <br />Imperial Valley of California, one of the richest farm- <br />ing areas in the country is looking at being returned <br />to desert as the excess flows from the Colorado River <br />are diverted by upstream states, or being sold to <br />meet the needs of growing California municipalities. <br />A major effort is being made in southwestern states <br />to eradicate tamarisk, a non - native streamside shrub, <br />because its water uptake is so great that it is depleting <br />stream flows. Even eliminating large stands of aspen <br />in the Rocky Mountains has been discussed in order <br />to increase runoff to mountain streams. <br />Sourcewater protection is not just a matter of <br />protecting the quality of our drinking water sup- <br />plies. The pressures on sources of water are making <br />our efforts to preserve and protect our water supplies <br />crucial, especially here in the West where every drop <br />is important. <br />AMERICAN <br />ENGINEERS & <br />S URVEYORS, INC. <br />Cade Benson P.E. <br />President <br />11031 S. Pikes Peak Drive <br />Suite #202, P.O. Box 574 <br />Parker, CO 80134 <br />12 <br />THE BLACK MAGIC OF <br />WATER MATHEMATICS <br />By David Orient <br />City of Grand Junction <br />This time I want to talk about percentages. Percentages are important <br />to understand, because in water treatment and distribution many times <br />chemicals are not at 100% strength. In everyday life we also use percent- <br />ages, if shoes are on sale at 30% off regular price, what will they cost? It is <br />also important when buying Beer. 3.2% does not have the same kick as full <br />strength. <br />Everybody knows that 100% of something is all of it. 100% of a gallon <br />is a gallon. 100% of 50 lbs. is 50 lbs. It is important to remember that when <br />you are dealing with something that is less than 100% it is not all of it, or <br />not full strength. <br />In water treatment chlorine is a good example. Liquid or gaseous chlo- <br />rine is 100% chlorine, while calcium hypochlorite is typically 65% available <br />chlorine. Calcium hypochlorite is used in some treatment plants to disinfect <br />water and it may also be used in newly laid water lines for initial disinfection. <br />Calcium hypochlorite is also called HTH, and can come in tablet or granular <br />form, but remember only 65% of it is chlorine. (Always remember to check <br />the package or MSDS sheet to determine the chlorine concentration) <br />Let's say a water treatment plant treats 2mgd and needs initial chlorine <br />dose of 3 ppm.The formula is (mgd)(ppm)(8.34) or (2)(3)(8.34) = 50.04 lbs <br />of chlorine.The 50.04 lbs you calculated is for 100% chlorine.You only got <br />65% available chlorine with this HTH stuff. The key question you have to <br />ask yourself is do I need more or less of this stuff? Remember the 3.2% <br />Beer.You need more for the same buzz. Now you could just add more HTH <br />till it feels right, but that's not a good idea. 100% = 1, all, pure, full strength, <br />everything,the whole enchilada.When 65% is written as a decimal it is 0.65. <br />Let's take these 50.04 lbs of pure chlorine you needed and divide it by 0.65, <br />which is 50.04 _ 0.65 = 76.99 This means you need to use 76.99, oh heck, 77 <br />lbs. of calcium hypochlorite to equal 50 lbs pure chlorine. But what if you <br />can't remember whether to multiply or divide by the 0.65? Just remember, <br />are you going to need more or less of this 65% material? MORE, so if you <br />multiply your original 50 lbs by 0.65 you get 50 x 0.65 = 32.5 lbs. WRONG <br />WAY DON'T DO THAT! <br />How about Sodium Hypochlorite? This stuff is a liquid (bleach). It comes <br />in several concentrations, typically 5% (bleach), 10 %, 15 %, and there are <br />probably others. The 5% bleach you can buy at the grocery store is the <br />most common. In the previous calculation you needed to use 50 lbs. pure <br />chlorine or 77 lbs. calcium hypochlorite. How about 5% bleach? There are <br />a couple of different ways to calculate this but I like this one. First I want to <br />know how many pounds of chlorine there are in a gallon of bleach. (It makes <br />me feel better to know this.) A gallon of bleach weighs about the same as <br />a gallon of water, 8.34 lbs. but only 5% of this is chlorine. Make <br />5% into a decimal. 0.05 (a word of caution here). If you have a % <br />Phone: 303.841.3922 <br />Fax: 303.841.3772 <br />cade.benson @am- engr- svr.com <br />key on your calculator you may use it or you can make 5%,0.05 <br />but don't do both. Let's say you have a % key on your calculator. <br />Put in 8.34 x 5% key (you know in this case you are looking for a <br />smaller number) = 0.417 Ibs.This means there is 0.417 pounds of <br />pure chlorine in a gallon of 5% bleach. Now if there is 0.417 lbs <br />chlorine in a gallon of bleach, how many gallons would you need <br />for your 50 lbs. dosage? 50 _ 0.417 = 119.9 gallons. <br />Now how about that $89.95 pair of shoes on sale for 30% off. <br />$89.95 x .30 = $26.99: $89.95 regular price — $26.99 discount = <br />$62.96, what a deal. <br />Remember that you have to subtract the discount from the <br />regular price. <br />