Thank you for the reply..
To make things further clear....
Do we have to design the building accordingly or Adopt depth as per site conditions??
For example, Say footing depth in a building is designed as 1.5 m below ground level. But on site, one of the footing lies in a depressed zone, so footing depth won't be 1.5 m in that footing. What should i do in such case?? DO I go deeper in that one particular footing OR Compromise on the footing depth OR Go deeper in rest of the footings to match the depth in that particular footing??