How could you reduce the water table to protect a structure?

The most effective method of keeping groundwater out of property is to intercept the water by means of a drainage system and divert it away from the house. The technique involves creating a ‘cone of depression’ beneath the property to prevent groundwater rising to floor level.

you can reduce groundwater table before and during construction process by using suitable dewatering system as deep wells system or sand drain according to type of the soil.no problem for rising of groundwater level again after finishing the construction and backfill

It is desirable to site any building on well-drained land However, other considerations such as access roads, water supply, existing services or a shortage of land may dictate a poorly drained area.

If a building site with poor natural drainage must be used, it may be improved by the use of contour interceptor drains or subsurface drains in order to cut off the flow of surface water or to lower the water-table level. Aparn from protecting the building against damage from moisture, drainage will also improve the stability of the ground and lower the humidity of the site. Figures5.1 and5.2 illustrate these methods.

Subsurface drains are usually laid0.6 to1.5m deep and the pipe layout arranged to follow the slope of the land. The spacing between drains will vary between10m for clay soils to50m for sand. Subsurface drains are usually formed from buttjoined clay pipes laid in narrow trenches. In cases where it is desirable to catch water running on the surface, the trench is back-filled nearly to the top with rubble either continuously along the trench or in pockets. A trench filled with rubble or broken stone will provide passage for water and is effective in dealing with flows on the surface. Pipes and trenches belonging to the main site drainage system may cause uneven settling if allowed to pass close to or under buildings. Where needed a separate drain, that surround the building and installed not deeper than the footing, is used to drain the foundation trench.

If applicable excavate drains/shallow wells at vantage points close enough to structure; atleast upto the invert elevation of substructure (about2-3 m away from structuture but deep enough for ground water to collect into it). pump water away continously to a safe place away from structure (spout from pump should always discharge downstream).

when this successfully done, water table will subside drastically.

You can improvement the soil with water table by adding cobbles and lumpsoff rock . Below the construction and make system to collect the water.

you can make deep wells with holes in ground to collect water in it by gravity , then you you can remove it by pump from these wells. 

i suggest u vaccum dewatering technique