Module 4 — Water Well Drilling Agreements
31
19.
Well cover
_________________
.
Distance from top of casing to ground surface__________________
Minimum requirement is 20cm (8") above ground surface or 60cm (2") above the highest
flood record unless a water tight cover is used. A water-tight, vented vermin-proof cap is ideal.
For large diameter wells, a tight-fitting, vented cover should be specified.
The well cap should be removable or be designed to allow access to a dip tube for ease of
monitoring the water level.
20.
Liner material_ _________________________________________________________________
Inside diameter____________ wt. per m(ft.)__________ wall thickness____________
See Water Well Casing and Specifications, page 33. Plastic PVC or ABS casing lasts
indefinitely because it does not rust like metal casing, however it must be protected at the
ground surface with metal casing.
21.
Screen Manufacturer_ ___________________________________________________________
Length _________________________________________________________________________
Material________________________________________________________________________
Nominal diameter_ ______________________________________________________________
Wells completed in unconsolidated aquifers, such as sand or gravel, should be screened.
The length of screen required depends on the volume of water to be pumped and the ability of
the aquifer to transmit water.
Yield Testing
22.
Yield testing duration (hours)_ ___________________________________________________
The licensed water well contractor should conduct a yield test following completion
of the well. It serves as a benchmark for monitoring future well performance. The test
should include the following information:
a) non-pumping (static) water level
b) water removal rate in gpm(L/s)
c) depth to the pumping water level as determined over a period of time at a constant
pumping rate(drawdown)
d) the length of time the well is pumped
e) the recovery of the water level over a 2 hour period or until 90 percent recovery of the
non-pumping water level is reached.
23.
Pump Type ________________ Size ____________________
The purpose of measuring the well's yield is
to gather enough information to determine
what pumping equipment will best ensure
adequate water pressure and prevent
damage to the well by over-pumping. Not all
licensed water well contractors include pump
installation as part of their business. Be
sure to select your pump contractor carefully
and provide them with the yield test data
collected by your driller.
It is important to get a good pump yield
test on the well when it is constructed.
This provides a base condition to which
the productivity of the well can be
compared as it "ages."
300
mm (12")
6”
well cap
Plastic Schedule 40 PVC
0.237
ABC Screen Co.
Sub
0.5
HP
102
mm (4")
Minimum: 2 hour water removal and 2 hour recovery