The sand replacement method consists of making a hole into the ground. The excavated soil is weighed. The volume of the hole is determined by replacement with sand.

Knowing the weight of excavated soil and the volume of the hole, the in situ unit weight can be easily determined. There are the following procedure for finding the unit weight of soil by sand replacement method is as follows:

1. The site is cleaned and a square tray with a central hole in it is placed on the cleaned surface.

2. A hole of diameter equal to the diameter of the hole in the tray and depth of about 10-15 cm is made in the ground.

3. The excavated soil is collected in a tray and weighed and its water content is determined.

4. The pouring cylinder is filled with sand to about 3/4capacity and its weight is taken and its density is also known.

5. The cylinder is then placed over the hole and tape is opened and the sand is allowed to run to fill the excavated hole and conical end.

6. when no further flow of sand takes place, the tap is closed and the bottle with the remaining sand is weighed. The weight of sand filling the cone of the bottle is taken separately. The observations and calculations are as follows:

Weight of soil in the hole =W_{1}

Weight of pouring cylinder + Sand before pouring=W_{2}

Weight of cylinder + Sand, after pouring=W_{3}

Weight of sand filling conical funnel =W_{4}

Weight of sand filling hole = W_{2}-W_{3}-W_{4}

Unit weight of sand = Gama

The volume of sand = (_{W1-W2-W3})/Gama = Volume of hole=V

Bulk density = W1/V