Methods for ground water control

METHODS FOR GROUND WATER CONTROL

The main methods used in civil engineering to eliminate the drawbacks due to the presence of water in the ground are divided into two groups:

1) Stop water flow methods include those systems that, once applied, prevent the water from flowing into the ground:
a) metal sheet piles;
b) concrete sheet piles;
c) concrete and plastic diaphragms;
d) injections;
e) freezing.

2) Dewatering methods include those systems that, once applied, determine a controlled lowering of the level of water in the soil.

If the water is intercepted within the excavation area, we have:
a) drainage with free embedding;
b) drainage with draining trenches;
c) drainage with booster wells.

If the water is intercepted before it reaches the excavation area, we have:

a) drainage with vertical wellpoint;
b) drainage with deep wells;
c) drainage with horizontal wellpoint;
d) welldrill drainage;
e) jet-eductor drainage;
f) electroosmosis drainage.

The table on the next page summarizes the various methods with the methods of execution and the types of soil suitable for their application.

Method Type of soil Execution
Metal sheet piles All types of terrain except for those large-sized rocky and gravelly pits Mechanical driving by percussion or vibration
Concrete diaphragms
Plastic diaphragms
All types of terrain including rocky ones With clamshell buckets and bentonite sludge circulation
Concrete sheet piles All types of loose soil Mechanical and water pressure piling
Injections All types of saturated soil, even rocky ones With core drilling and high pressure filling
Freezing All types of saturated soils With core drilling (liquid nitrogen and CaCI2 brine)
Free draining Carry-over and gravels Direct suction
Draining trenches Stratified clays Excavation and filling with drainage material
Booster wells Carry-over and gravels Excavation and filling with drainage material
Vertical Wellpoint Sands, gravels, silts and clays Pitching at water pressure and / or compressed air
Drainage wells Sands, gravels and rock layers Percussion or rotation drilling
Horizontal Wellpoint Fine sands and stratified sands Laying with open excavation or with soil-laying machines
Wellpoint jet-eductor Sands, silts and fissured soils Piling up by water pressure, rotary drilling
Electroosmosis Lime, clayey silts and peat With coring and / or driving