Land quality – managing ground conditions

4.1.3Initial Assessment – walkover survey (all sites)

To assess ground conditions, a walkover survey of the site and the surrounding area shall be undertaken by a suitable person.

A walkover survey is a direct inspection of the site and the surrounding area carried out in conjunction with the desk study. Indications of any potential hazards should provide a basis for the investigation. A photographic record of the site can help in the reporting of the walkover survey.

Table 2: Potential hazards

Source of informationItems to be taken into account
Topography■ abrupt changes in slope
■ valley bottoms or depressions which may be soft or filled
■ evidence of overburden on slopes
■ excavations at the base of the slope
■ signs of landslip, e.g. tilting trees, posts or walls
■ signs of subsidence
■ evidence of imported soil including local surface depressions, tipped material or rubbish, particularly if it is hot or has an odour.
Soils and rocks■ the basic ground type
■ evidence of peat, silt or other highly compressible material at or below the surface
■ cracking or stickiness of the surface which may indicate a shrinkable sub-soil
■ sudden changes in conditions, e.g. clay to chalk or soil to rock.
Surface water and vegetation■ a high water table indicated, e.g. by waterlogged ground
■ signs of flooding
■ reeds or water-loving plants
■ springs, ponds, wells, ditches or streams
■ the source of any discoloured water.
Vegetation■ vegetation which may indicate the nature of the soils
■ sparse dead or dying vegetation
■ type and condition of vegetation on land adjoining the site
■ species, height and condition of the trees
■ species, height, spread and condition of hedges and scrub on clay
■ evidence of former trees, hedges or scrub on clay.
Structural information■ damage to structures, e.g. cracking in buildings, on or around the site
■ other evidence of movement, e.g. tilting or distortion
■ any structures or services below ground.
Local information
■ local knowledge of the site, e.g. mining, refuse tipping or flooding
■ local industrial history records indicating past and present uses of the site
■ place names and street names that may give clues to previous site usage,
e.g. Brickfield Cottage, Water Lane.