Site Investigation Strategy

Abstract

Regardless of project size and location, be it in the centre of a city, in the outskirts, or on virgin land, the principal steps of a site investigation are the following:

• During the desk study all available information is collected in order to understand the ground conditions at the site under consideration. Since urban land has already been used by man or affected by his activities, information on the human impact has to be gathered as well. A first orientation visit on the site is compulsory.

• During the phase of field reconnaissance a map is prepared featuring relevant aspects of geology, hydrogeology, geomorphology, as well as flora and fauna and the human impact. Relicts from former utilisation, foundation fragments, contaminated sectors, dump sites, etc. indicate the grade of urban land degradation. If bedrock is exposed on the site it is evaluated with special attention given to tectonic features and fracture patterns. Soil and rock samples are taken and simple field tests — index tests — are conducted in order to identify the types of soil and rock present, their strength characteristics, and their grade of contamination. Furthermore, goods to be protected are documented. Besides surface- and groundwater resources, the ecosystem, flora and fauna, etc. these include buildings, roads, and other items of given infrastructure that can be reused after the redevelopment of the site or during its remediation. In order to avoid unjust claims of compensation that might be put forward in the course of a project a detailed documentation of the status quo is necessary.

• During the field investigation the geological and hydrogeological condition are investigated with more sophisticated equipment. Special field tests are carried out to measure the strength properties of the subground and to analyse the hydrogeology of the site. Samples taken during field investigation are analysed by specialised laboratories. Standard tests include the analysis of the composition and structure of the samples, their strength properties, as well as hydraulic characteristics and contamination grade. Mobile laboratories permit a rapid and interactive analysis of samples on site and can therefore facilitate the visualisation and interpretation of ground conditions.