If a site survey has not been done, or provided by the client, then a topographical survey should be carried out. The survey should show the site location and access, give site boundaries, building lines, position of proposed structure, levels and contours, benchmarks and survey stations or reference points. In addition, information should be shown on such conditions as previous workings, overhead lines, underground services, evidence of drainage or ﬂooding, condition of adjacent structures and other easily detectable and useful evidence.
2 Study of existing information
There is often quite a surprising amount of information available for many sites and the surrounding area – even green sites in undeveloped areas – and a study of this information can be invaluable in planning an efﬁcient and economical soil survey.
Valuable sources of information are listed below:
(1) Ordnance Survey maps (old maps are often useful in providing information on any previous use of the site
which may not appear on revised up-to-date maps).
(2) Geological survey maps, both solid and drift; the Institute of Geological Science Records; Soil Survey and Land Research Centre (SSLRC); The Land Utilization Survey; The Coal Authority can often supply information on proposed mining, present, past and abandoned workings, and ﬁnally the Institute of Materials, Minerals and Mining may have records of other extractions such as tin mining in Cornwall and brine extraction in Cheshire.
(3) Aerial survey photographs which may be of use can be sourced via the National Association of Aerial Photographic Libraries (NAPLIB).
(4) Local authorities’ building control ofﬁces and inspectors often have detailed information on any previous
use of the site, local conditions and records of previous investigations.
(5) Local contractors frequently know of behaviour and construction difﬁculties of excavation, together with records of ground condition and type in the locality.
(6) Local people, such as miners, quarry workers and grave-diggers, can be helpful (sometimes they can be
‘overhelpful’ in telling what they think the investigator wants to know with the temptation to embroider their information).
(7) Local Planning Authorities. It is essential to contact them to determine any planning conditions or restric-
tions for the proposed structure and such matters as rights of light, way and support. They can also advise
on site access for plant and transport, noise and other nuisance restrictions. They may also have information on existing or proposed services below ground level, i.e. water mains, sewers, other service pipes, etc., and similar information on overhead power lines, and can put the investigator into contact with the public utility
authorities. The planning process will now generally result in a number of detailed requirements for the implementation of a site investigation and a list of conditions to be discharged before redeveloping a
previously used site.
(8) Public Services Authorities. Utility services for telecommunications, gas, water and electricity usually
keep up-to-date records.
(9) Local street and area names. Sometimes local place names may indicate previous use. Typical names are
Brick Kiln Lane, Quarry Bank and Marsh Street.
Since many people in the above list of information sources are busy it has been found from experience that it can be quicker and more efﬁcient to go and see them to discuss the site rather than engage in long drawn-out correspondence.
It is not uncommon in such discussions to discover valuable information which may have been unexpected, not known to exist or not asked for.