Backwashes and overpumping

Backwashes and overpumping

As violent as the two methods of surging may seem, and as forceful as jetting may be, it is always best to begin development procedures gently.

This can be done with the simple air lift pumping action which precedes the first blast of air in the last method.

Accordingly, some ways to develop wells remain rather gentle, as with backwashes created by pumping water to ground level of a deep well and then letting it fall back.

A deep well turbine without a foot valve is often used for this purpose, although an air lift is applicable here, too.

Alternatively, water can be pumped to fill a large tank from which it is all released at once to provide a stronger backwash.

Generally, the surging action provided by backwash methods is not enough to develop a well to its full potential, although there are cases where they have proved satisfactory.

Similarly, overpumping is not apt to provide the best development, but this is the simplest way to remove fine particles from the aquifer.

It does no harm, because any well which can be pumped at a high rate certainly can be pumped at the lower rate for which the well is designed.

However, it can leave bridges of sand grains and an only-partially-stabilized well.

Its best application is for small wells or those in poor aquifers with few fine sands to cause problems.

Large wells would call for pumps of capacities not always easily available.