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Module 4 — Water Well Drilling Agreements
15.
Annular or casing seal_ _________________________________________________________
All wells must be constructed to prevent contaminated surface water from entering
groundwater aquifers through the annulus (or space) between the outside of the well casing
and the borehole. The annulus must be filled from immediately above the producing zone up
to ground surface. The method of sealing is dependent on the type of rig the driller operates
and the design of the well.
16.
Artificial sand pack______________________________________________________________
The grain size distribution of the aquifer affects the efficiency of the screen during
development. If the aquifer has a relatively uniform fine grain size, a well cannot be effectively
developed without the installation of an artificial sand pack. This "pack" provides a natural
filter which holds back the finer aquifer materials.
17.
Well Development Method
Backwashing__________ Jetting__________ Surging__________
Heavy pumping__________ Bailing__________
By regulation, the licensed water well contractor is responsible for ensuring a well is
completed in a manner that ensures no damage will be incurred to the pumping system,
plumbing or fixtures due to sediment in the water. If a newly constructed well produces
sediment, it is usually because the licensed water well contractor did not properly develop
it. Different types of well completion require different development techniques. In the rare
case where a well cannot be adequately developed to produce sediment-free water, a sediment
filter could be installed in the water distribution system. However, this alternative should be
used only when it is evident that sufficient development of the well has been done, and the
landowner is in agreement.
Material
18.
Casing material_ ________________________________________________________________
Inside diameter____________ wt. per m (ft.)___________ wall thickness___________
See Water Well Casing Specifications, page 33.
Bentonite
Good well design, construction and material
selection is necessary to reduce the effects
of natural corrosion, biofouling and
incrustation.
Plastic Schedule 80* PVC * Steel Protector casing at Surface
0.375
127
mm (5")
X