Water distribution practice exam #2 (D1-D2)Accurate 100%

Which process converts ammonia to nitrite and nitrate? - ANSWER Nitrification What is the maximum advisable rate of chlorine gas removal from a 150- pound cylinder? - ANSWER 40 pounds per day What is a type of positive displacement water meter? - ANSWER Nutating- disk meter What is a power-operated mechanism for opening and closing a valve? - ANSWER Actuator What is required if a routine sample test positive for total coliform bacteria? - ANSWER Take repeat samples Why is a grid layout better than a tree layout for a water distribution system? - ANSWER Less dead-end mains What is the purpose of a reduced pressure principle assembly? - ANSWER Prevents back-pressure and back-siphonage In general, at what depths is shoring required for a trench, if you're excavating in soil? - ANSWER 5 feet or deeper What occurs after breakpoint chlorination is achieved? - ANSWER Free available chlorine residual is directly proportional to the amount of chlorine added What is used to automatically shut-off the flow into a tank when the water level reaches a pre-determined level? - ANSWER Altitude valve What would be used to find a chlorine gas leak, which produces white smoke when it reacts with this substance? - ANSWER Spray ammonia solution vapor near leak What causes staining of plumbing fixtures? - ANSWER Iron & manganese How long should you flush water before you collect a bacteriological sample? - ANSWER As long as necessary to flush stagnant water from the service pipe What is the purpose of a surge tank? - ANSWER Protect pipelines from sudden high pressure What is recommended if a chlorine gas cylinder is leaking? - ANSWER Rotate the cylinder and turn the leak upwards What is the purpose of primary MCL? - ANSWER To protect human health What problem could be used by water with a pH of 5.3? - ANSWER Corrosión What is a common way to connect a new pipe to an existing pipe, while the latter is pressurized and in-service? - ANSWER Wet tap or hot tap What impact would organics have on chlorine demand? - ANSWER Increase chlorine demand What is dichloramine? - ANSWER Combined chlorine residual What impact does tuberculation have on the interior of a water main? - ANSWER Causes rough interior of the water due to corrosion What is used to neutralize chlorine residuals when collecting a water sample for bacteriological analysis? - ANSWER Sodium thiosulfate What are electrodes and ultrasonic signals used for in a tank? - ANSWER Monitor water level Which part of the water main should a new service tap be installed? - ANSWER 45 degrees from the top of the water main