Water Supply Flashcards
What are the strategic issues?
Drought Leakage Risk of critical infrastructure failure. Stormwater contamination. Affordability. Foul sewer overflows and property flooding.
What are the water supply sources?
Groundwater bores. Reservoirs. Stream/river offtakes. Lakes. De-salination. Roof water. Process water resuse.
How does the chch water supply work?
- Water from bores (aquifers)
- Pumped up to port hills (through mains) to a storage facility (multiple storage tanks the hill)
- Gravity fed from storage tanks to houses (local water pipes) etc. Pumps switched on if need be. This is monitored from a control room.
What size are the chch wells? and how many per site? how deep?
200 to 300 mm.
up to 5 per site.
22 to 190 m.
How many kms of main pipes exist in chch?
1300 kms with tot piping = 1500 kms (+submains)
What are the pipes made from in chch?
Castiron with cement coating.
Fibrolite.
Plastic.
How are the pipes laid out in chch?
So that if a pipe needs to be isolated for repair then water supply will not be cut off for the consumer.
What is Auckland’s water supply from?
100% dams
Key things when designing a water supply system?
- Water quality
- Hydraulic capacity
- Structural strength of water system components
- Fire supply
- Fit for purpose
- Seismic resistant
- Resist corrosion
- Whole life cost for 50 year
- Ability to be altered and extended.
- Networking
Approximate water use per day?
180 - 250 L
Summer can raise this.
What area uses the most water?
Industrial
What are the high industrials water users?
- Food processing
- Beverages
- Textiles
- Pulp and paper
When doing calcs, what is the minimum water demand?
250 L/p/day
What need needs to be calculated for design flow and pressures for residential?
Minimum water 250 L/p/day
Peak flow
Fire water demand
What need needs to be calculated for design flow and pressures for Business zones?
Minimum water demand
Peak flow
Fire water demand.
What are the rules around fire water supply?
Needs to be sufficient water to put out fire as a delay in access to water will lead to potential loss of lives.
What is the equation from calculating the maximum operating pressure? (m)
Max = Hs + S - E
- Hs = static pressure (m)
- S = surge allowance (m)
- E = lowest ground level of the proposed main (m)
What is the minimum pipe class for reticulation mains?
PN 12.
For fittings PN 15.
When is a pipe susceptible to surges? (pressure transients)
When the flow of fluid is abruptly changed. Caused from quick acting valves, or pumps that stop and start quickly.
How many times are pipes rated operating pressure?
1.5 times.
Issues with ductile iron and steel?
Stray electric currents and bimetallic corrosion.
Internal lining and external coating must be fully repaired.
Issues with PVC-U?
Pressures do not exceed 1.25 times rated pressure. blah blah
Issues with PE 80, and PE 100?
blah blah blha
What are the typical pipe fittings?
- Sluice valves
- Backflow prevention
- Scour valves
- Air valves
- Thrust and anchor blocks
- Meters
What are the two causes of backflow?
- Sudden drop in pressure, causing a siphon effect.
- Water supply connected to something of higher pressure forcing supply back.
What is backflow prevented?
Because it can cause contamination.
High = toxic
Medium = endangers health
Low = nuisance
What considerations must be made when installing pipes?
- Installation methods
- Min conver
- Backfill and bedding mats
- Crossings (road, river etc)
- Future access
- Environ, topo considerations
How does pumping a well effect other wells?
Pumping from one could reduce the intake from another.
WEll stuff etc was left
lefrgea
