Site Investigation is the gathering of information about the proposed location of the construction project. The reason for this can be twofold, firstly to assist in the location of the project and secondly to ascertain ground conditions. A site investigation should be taken for every site. Without a properly procured, supervised and interpreted site investigation, hazards which lie beneath the site cannot be known.
A site investigation is made up of five parts –
1) Desk Study
The desk study is work taken up prior to commencing the work on site and the Ground Investigation. It should always be the first stage of the Site Investigation and is used to plan the Ground Investigation. The work involves researching the site to gain as much information as possible, both geological and historical.
* Geological Maps and memoirs are probably the most important source of information as these give an excellent indication of the sort of ground conditions likely to be encountered. It gives a good indication of the types of material and the structures occurring in the region.
* Arial Photography is another extremely useful source of information. These records can be obtained from one of several sources such as the Department of the Environment, local authorities and air-survey firms. Such records can be extremely useful in getting a good knowledge about the topography of the land.
* Records of Previous Site Investigation reports are also helpful in a desk study.
2) Site Reconnaissance
The Site Reconnaissance phase of a site investigation is normally in the form of a walk over survey of the site. Important evidence to look for is:
Hydrogeology: Wet marshy ground, springs or seepage, ponds or streams and Wells.
Slope Instability: Signs of slope instability include bent trees, hummocks on the ground and displaced fences...