Excavation refers to the process of moving earth using different kinds of specialized equipment to clear unwanted soil and make room for the foundation on a construction site. It helps create the foundation for buildings and roads and make room for construction of reservoirs, pools and structures that go below ground level. The four major types of excavation are as follows:
Topsoil excavation involve the removal of the exposed layers of the earth's surface. It includes removal of existing vegetation, decaying matter and anything that makes soil compressible and thus unable to bear significant structural loads. The depth of topsoil excavation varies depending on the structure and the kind of soil available. Topsoil contains moisture and supports the growth of trees and vegetation. The excavated top soil is still usable and should be stockpiled and later restored on the site during landscaping. It helps in this case to restore vegetation and control erosion.
This is the excavation of the second layer of soil usually found right underneath the top soil. This kind of excavation is generally much easier to carry out because the earth underneath the topsoil is loose. The removed soil has less moisture than the top soil and can be stockpiled and used for filling of embankments and foundations.
This is the removal of excessively wet soil (muck) especially in wet and damp areas. Excavation of muck involves the use of special drainage equipment to channel away excess water from the site and special excavators to lift the wet soil and load it onto trucks. The excavated soil is unsuitable for any construction work and thus cannot be stockpiled for later use. The high moisture content makes the excavated material unstable. The only way to solve this is spreading it over a large area for quicker drying. Other materials may be used to reduce water content.
This is the removal of the tough part of the earth's surface. Rock excavation requires the use of special type of equipment like excavator-mounted hydraulic hammers and explosives, especially for large areas. Due to the risk involved, rock drilling has to be carried out under very careful coordination. The technique to use depends on the intended depth of the excavation, the proximity of the site to surrounding structures and presence of any hazardous areas. In addition, due to the high risks involved, you need to have special expert supervision and permission from the relevant authorities depending on the site before you can carry out any excavation using explosives.