B Test Material - TCEQ Class B Surface Water Exam Review Questions And Answers

B Test Material - TCEQ Class B Surface Water Exam Review Questions And Answers What is the most important factor affecting the useful life of service lines? - ANS-It is the ability of the material to resist internal and external corrosion When does Suction Head exist? - ANS-Suction head exists when the source of supply is above the centerline of the pump. What is Net positive Suction Head (NPSH) - ANS-NPSH is the pressure under which water enters the eye of the impeller in a centrifugal pump. Insufficient NPSH is the main cause of pump cavitation Explain and expand on Chlorine Dioxide (what it reacts with, oxidizes, etc) - ANS-Chlorine Dioxide is a gas used in small quantities to disinfect water. It does not react with organics to form THMs and HAAs. It oxidizes phenols, manganese, iron, sulfurous and organic compounds which aids in the removal of tastes and odors. It is a very effective bactericide and a superior virocide. It dies not combine with ammonia. Chlorine Dioxide MRDL is .8 mg/L and monitoring procedures are the same as for chlorine. The Chlorite MCL is .q mg/L and must be monitored daily. What is texas drinking water pH requirements? - ANS-The texas drinking water requirements require a pH > 7.0 for the water treatment plant finished water. EPA requires that pH analysis be preformed within 15 minutes of the sample being caught. How does pH affect Chlorine activity? - ANS-When chlorine is added to water it forms hypochlorous acid (HOCL) and hydrochloric acid (OCL). The hypochlorous acid is the effective disinfectant. At a pH of 4.0 there is 100% hypochlorous acid. At a pH of 11 there is 100% hypochlorite ion. At a pH of 7, the hypochlorous acid is at about 80% and the hypochlorite ion makes up about 20% of the chlorine content. The lower the pH is more effective chlorine is because you have more hypochlorous acid. What is meant by water stability? - ANS-Stable water is defined as water that will neither deposit or dissolve a calcium carbonate film or scale. Since no water is stable indefinitely, chemical treatment of water usually is intended to produce water that is slightly scale forming without being liable to cause stoppages in small lines and services. Bayliss curve is the simplest determination of stability. The Langelier saturation index is also used. What/how are above ground tanks and piping protected from corrosion? - ANS-Corrosion protection for above ground tanks and piping is prevented by: cathodic protection, use if protective linings/coatings, eliminating different types of metals in the distribution system, and treating the water with chemicals to make it less corrosive How do you tests fir alkalinity? - ANS-... Continues...