Basic Water Treatment Questions and Answers Graded A

Basic Water Treatment Questions and Answers Graded A In Texas, water operator licensing is administered by the ________. TCEQ Which minerals cause hardness in water? Magnesium and Calcium The most important federal law impacting the water utility industry is the ________. Safe Drinking Water Act The four water quality standards established for drinking water in the Safe Drinking Water Act are chemical, bacteriological, radiological and ________. physical The minimum allowable pressure in the distribution system under emergency conditions is ________. 20 psi Water vapor given off by plants and trees is known as ________. transpiration Organic matter includes ________. wood, dogs, algae, bacteria The single most important water treatment process is ________. disinfection Excessive nitrates in drinking water can cause ________ syndrome in infants. blue baby A sanitary control easement must cover land within ________ feet of a public water well. 150 A sample for physical and chemical analysis of a new well must be taken after ________ hours of continuous pumping. 36 Chapter 290 Rules and Regulations require chemical analysis of surface water supplies every ________. year Detention time in sedimentation basins must be at least ________ hours to allow floc to settle. six Backwashing should expand the filter media by ________ percent. 30 to 50 In Texas, all public water systems are required to have ________ facilities. chlorination The MCL for Trihalomethanes in drinking water is ________. 0.080 mg/L At room temperature, chlorine gas is greenish-yellow, has a pungent odor, and is ________ times heavier than air. 2 ½ Diseases that may be spread by inadequately disinfected water are ________. typhoid, cholera, infectious hepatitis, and legionnaires disease Minimum chlorine residuals of ________ (free) and ________ (combined) are required in the far reaches of the distribution system. 0.2/0.5 mg/L Parameters that affect coagulation are ________. turbidity, pH, alkalinity, coagulant type, and dosage Do not work in a trench ________ feet or deeper unless it is protected from a cave-in. 5 Place spoil banks at least ________ feet from the edge of an excavation. 2 Dose new water mains with a minimum of ________ mg/L or more of chlorine for at least ________ hours. 25/24 or 100/3 or 500/.5 (30 minutes) One bacteriological sample is required for each ________ of new completed main. 1,000 feet A cross connection is a physical connection between a public water supply and 1) another supply of unknown or questionable quality, 2) any source that may contain contamination, and 3) any water ________. treated to a lesser degree Maximum spacing between ladders in a trench is ________. 50 feet When should a rapid sand filter be backwashed? Loss of head of 6 to 10 feet, filter NTU is 1.0 or above A ditch 4 feet wide, 6 feet deep and 1,000 feet long will be excavated. How many cubic yards of pipe bedding will be needed to bed the trench 7 inches deep? 86 . (4 x 1000 x .58) / 27 = 85.9 How many gallons will 5,000 feet of 18 inch water pipe hold? 66,100 gallons 3.14 x .75 x .75 x 5000 x 7.48 = 66,057.75 18 x 18 x .0408 x 5000 = 66,096 A tank that has a capacity of 700,000 gallons must be disinfected with a dosage of 50 mg/L of chlorine. How much 65% HTH will it take to achieve the same goal? 449 pounds (.7 x 8.34 x 50) / .65 = 449.07