What is the maximum population that can be served by a Class 1 Water Distribution System?
1500 People
What 2 factors determine the number of distribution system samples to be taken each month for Bac-T testing
1: Population
2: Raw Water Quality
What publication describes recommended limits for substance and conditions that affect drinking water in Canada?
Guidelines for Canadian Drinking Water Quality - Latest Edition
What authority is responsible for regulating water supply systems?
Provincial Environment Dept
How is a water treatment plant’s classification derived?
A point system based on complexity
What are the most common forms of chlorine used for field disinfection?
Calcium hypochlorite and Sodium Hypochlorite
What type of pipe does not need cathodic protection
PVC pipe
What is the main objective of a water distribution system?
To maintain a minimum positive pressure at all times and protect potable water from contamination
What value determines a if a pipe has low friction loss
A high C value
What is a hydraulic grade line?
A hypothetical line used to indicate the relative pressure in a system
What is the risk of a distribution system falling below atmospheric pressure?
Low or negative pressure may result in contamination from infiltration,back flow , or cross connections
What is the normal range of distribution pressure that should be maintained?
40-80 psi (280-550 kpa)
What is the purpose of a thrust block?
To provide support for the pipe where the flow changes directions
What is meant by “water hammer”
A pressure wave caused by rapid increase or decrease of water velocity in a piping system
Explain the main function of a treated water reservoir
To provide storage for later demand and reduce the required size and capacity of mains and booster stations
What are the most common types of pipes used in distribution?
PVC, AC, Steel, and Ductile Iron
Name 2 reasons proper bedding is inportant
1: Pipe support
2: Reduction of earth loads on pipe
What is the normal pressure for pressure testing a distribution system main?
150 Psi (1,000 kpa) or 1.5 times operating pressure - whichever is the greater number
In areas of high water tables, how can hydrant freezing be prevented
Plug and pump out hydrants
Choose 3 methods of controlling corrosion of metallic components of a distribution system
1: Chemical additives (lime, soda ash, orthophosphates)
2: Cathodic Protection
3: Non-Metallic Coatings (epoxies, silicate paints)
Why is reservoir (treated water) level control important
To prevent pump damage caused by low levels, to avoid overflow, and to avoid water loss
What factors must be considered when panting a steel tank?
Surface preparation
Effect on water supply
What are two ways to prevent freezing in treated water reservoirs?
1: Varying the water level frequently
2: Re-pumping/circulating the reservoir contents
What are 2 reasons why water distribution quality should be monitored
1: Confirming potability
2: Responding to consumer complaints
