ayotoyin:
Kindly go for Soil test to determine the best type of foundation to be used on that site. Its easier to ask for raft or pile, but safer to do soil test to guide your final decision.

waloma:
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Guyman02:
Foundation (or, more commonly, foundations) is the element of an architectural structure which connects it to the ground, and transfers loads from the structure to the ground. Foundations are generally considered either shallow or deep. (Wiki)

Pile foundation is quite costly and applied especially where you expect some level of vibration like in a factory or a plant.

You will need to some Excavation in a water logged area like you mentioned which should be at a depth of between three to five feet deep in the ground. This is done because when you set up a house without first considering what effect water will have on it, chances are that you might end up incurring double stretching expenses. After excavating about five feet deep, its always advisable to first lay a layer of hard core stones that are relatively bigger in size and not soil as most people do, reason being water from underground easily penetrates through soil. If available, the use of a hand or mechanical operated compressor is advisable to compact and compress the stones together.

After laying hard core stones, they should be followed by relatively smaller stones (gravel) and then a heavy heap of soil that should also be compressed to fill the gaps left unfilled by stones. This is done to ensure that there are no spaces left to prevent easy penetration and spillage of water.

It is then advisable to leave the newly laid foundation for some time of about three to six months for an area that is seasonally water logged and six to 12 months for an area that is averagely water logged before the final work plan of building is set up. This is because the compressed stones and the disintegrated soil must be given room to fully attach itself together to attain a firm and strong foundation.

The area where the new foundation has been set up should be cordoned off in a fence and proper drainage channels put up around it to prevent occurrences of massive erosion of the soil that has been compacted.

I can only talk about the cost of doing piling foundation which cannot be advised for you do to do due to the cost involved. Perhaps if I have time I can consult with others in the field on how much cost per square meter and height of filling and materials you may require.
Cheers!