How does the water quality in soil improves?
Improvement of water quality through soil passage
How can groundwater be recharged?
- Bank filtration
- Infiltration basin
- Sink-hole
What is artificial groundwater?
- Enriched groundwater (Infiltration via basin)
- Enriched groundwater (Infiltration via sink-hole)
- Bank filtrate (Infiltration via river bed)
Why should the flow time between river and drilled well be > 50 days?
To ensure that beacteria etc. die
What is the difference between bank filtrate and natural groundwater regarding:
- Groundwater table
- water level height
- temperature
- chemical composition
- bacterial composition
Groundwater table
- BF: Groundwater table fluctuates
- NG: Groundwater table fluctuates a little
Water level heigth
- BF: Drawdown in the riverbed changed with constant extraction, e.g. due to silting of the riverbed or low water leveld
- NG: Constant heigth with constant extraction
Temperature
- BF: Temperature changes with increasing distance from the well
- NG: Same temperature
Chemical composition:
- BF: Changing chemical composition
- NG: Only long-ter cahnges
Bacterial composition:
- BF: Bacterialogical composition changes, bacterial count high at times
- NG: Bacterial count low and constant
What is the area of application for driven wells?
- Low water demand (individual farmsteads, garden irrigation, water supply for grazing animals)
What is the lift height of driven wells?
6 - 7 m
What is the function of a well manhole?
Mounting of the extraction pipe with throttle valve, water meter, sand meter, areation and ventilation pipe, manhole ladder and piezometer
What is the function of a wellhead?
Sealing structure for tight closure, clamping of the top pipe
What is the function of an attachement pipe?
- Shallow wells: Guide as filter attachement pipe up to the wellhead
- Deep wells: Filter pipe is inserted approx. 5 m into the attachement pipe (no direct connection)
What is a filter pipe?
Most important part of the well, the filter pipe plays a decisive role in the effectivness and services life of the well
What are the tasks of a filter pipe?
- low filter resistance
- sand-free operation
- resistance to corrosion
- mechanical strength
- suitability for drinking water purposes
How are filter pipes generally constructed?
Gernerally constructed with gravel filter accoirding to DIN 4924
What is a sump pipe?
At the end of the filter pipe as pump sump, sludge trap, usually 1 to 2 m long, resting on 50 cm gravel fill
What is an extraction pipe?
Water inlet of a submersible pump at least 1 m below the lowest drawdown level (air intake)
Where are pumps arranged?
- In the sump pipe
- 1 m above the filter pipe
- Installation of a dummy pipe in the suction area of the pump
What is a gravel filter made of?
Cleanly washed quaurtz gravel filter, round grain shape: U = d_60/d_10 < 1,5
What is the minimum thickness [mm] with simple grain classification after DIN 4924?
- 0,25 - 2
- 2 - 8
- 8 - 31,5
- 0,25 - 2: 50 mm
- 2 - 8: 80 mm
- 8 - 31,5: 100 mm
What are the dimensioning rules for gravel filter?
- 80 % rule (D = d_80*4)
- Standard grain method according to BIESKE (1961)
- Filter factor rule (DVGW W 113)
How do you calculate the filter grain size?
Filter grain size = Filter factor (4,0 to 5,5) * standard grain size
