Desk study

A desk study is usually the first phase of a site investigation and is necessary to obtain optimal results of the subsequent phases. It includes the collection, review and verification of information already available about a site, and identifies potential areas of information conflict or deficiency. It is carried out at an early stage of site appraisal to guide the remainder of the site investigation. Depending on the location of the site (offshore, nearshore or onshore) desk studies may also include a visual inspection of the site and its surrounding area (usually called a walkover survey). 

The desk study needs to consider a broad range of issues, all of which may affect a project both practically and logistically. The desk study should include a review of all sources of appropriate information including historical records, and collect and evaluate all available relevant data for the site including, for example  

In any desk study of seabed conditions, a qualitative and quantitative assessment of existing data is mandatory. Potential sources for information and data sets include companies with proprietary data, national geological survey organisations, academia, other maritime operators and Contractors. Internet sites contain meteorological data for some offshore regions, but sources need to be checked and the data verified. 

Invariably, the sources for this information cannot be held hable for the accuracy, or relevance, of their information and therefore it should be used with discretion at the engineer s (or user s) risk. Much third party information will have copyright or other restrictions applied to its use and these should be properly researched, and where necessary the owners permission sought, before being cited. 

Often a desk study is considered the most cost effective part of a site investigation. They provide early recognition of the characteristics of the site and potential geohazards by  

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For a good design one often needs to do research - to make desk studies, try out things in the workshop, and - especially - experiment in the laboratory or in the field. This work can be applied and practical, but also very fundamental. However, the research part of product development differs from the largely curiosity-driven and exploratory research of many university departments in one important way it does not go further than needed for the development of the product. Time is a real constraint in development ... 

The European Commission s Food and Veterinary Office carries out Community controls in the Member States and in third countries in order to check their national control systems. On food contact materials, until now, desk studies on the systems in place have been performed. 

Preselection of the most suitable equipment for a project can be a desk study and may also include information on prior history and experience of others for... 

New information gathered from additional desk studies and any site investigation is then collated and used to provide more complete descriptions of the candidate source-pathway-receptor pollutant linkages identified in the Phase la report. Each linkage is considered separately and estimates are made of the extent and strength of the contaminant source, its connectivity to the receptor and the level of hazard that is presented to the receptor. Finally, a preliminary assessment is made of the potential harm that hazards may pose to the receptors. From this analysis it is likely that one or more pollutant linkages will be recognised as the... 

A desk study is undertaken as the first stage of a site investigation in order to make an initial assessment of the ground conditions and to identify, if possible, any potential geotechnical problems (Herbert et al., 1987). In other words, the objective of a desk study is to examine available archival records, literature, maps, imagery and photographs relevant to the area or... 

A desk study for the planning stage of a project can encompass a range of appraisals from the preliminary rapid response to the comprehensive. Nonetheless, there are a number of common... 

The importance of the preliminary investigation is that it should assess the suitability of the site for the proposed works, and if it is suitable, it will form the basis upon which the site exploration is planned. The preliminary reconnaissance also allows a check to be made on any conclusions reached in the desk study. 

Table 7.1. Summary contents of engineering geological desk study appraisals (after Herbert et al., 1987). With kind permission of the Geological Society...

There are no given rules regarding the location of boreholes or drillholes, or the depth to which they should be sunk. This depends upon the geological conditions and the type of project concerned. The information provided by the desk study, the preliminary reconnaissance and from any trial trenches should provide a basis for the initial planning and layout of the borehole or drillhole programme. Holes should be located so as to detect the geological sequence and structure. Obviously, the more complex this is, the greater the number of holes needed. In some instances, it may be as well to start with a widely spaced network of holes. As information is obtained, further holes can be put down if and where necessary. 

Purchas (1981) has suggested a selection system consisting of three selection steps to produce a shorthand profile of the application from a combination of desk study to define the required duty, and some simple laboratory testing to characterize the separation properties of the solid-liquid mixture. The profile is expressed as a sort of code formed from a group of alphabetic letters (e.g., bdh-BEG-K), and is used in a fourth step to select suitable... 

Ground information comes from ground investigations including desk studies, field work and laboratory testing. 

At the end of the leeture eourse all students undertake a mini-projeet outlined in Figure 3. Working in groups of three, they interpret a borehole log, undertake desk studies and plan investigations for specific developments. The sites ehosen are all in the Bristol region and the geologieal map is made... 

Within the scope of the research on the stability of open slope revetments, much knowledge has been developed about the stability of rock under wave and current load and stability of placed (pitched) stone revetments under wave load. Until recently, no or unsatisfactory design tools were available for a number of other (open) types of revetment and for other stability aspects. This is why the design methodology for placed block revetments has recently been extended in applicability by means of a number of desk-studies for other (open) revetments ... 

Knight S, Knightley S, Bingham I, Hoad S, Lang B et ai, HGCA Project Report 502, Desk study to evaluate contributory causes of the current yield plateau in wheat and oilseed rape,HGCA20 2. 

A desk study and site investigation report should be submitted with a planning application... 

The risks posed by the presence of gas cannot be assessed by looking at gas monitoring results in isolation from other data. A comprehensive desk study and site investigation are required to identify all the likely sources of gas below a site and their generation potential. This will allow the identification of potential sources such as mineworkings (these are particularly difficult to assess based on gas monitoring results as very large volumes can be emitted sporadically via discrete pathways, thus the gas emissions tend to be sporadic and spatially variable). 

If the source of the gas is unknown then the risk cannot be assessed. A low concentration of gas that is caused by migration from an adjacent domestic landfill is of much more concern than a high concentration that occurs from a limited source such as occasional fragments of wood in fill material or pockets of peat. This is very difficult to identify from gas monitoring without supporting desk study information. Anomalies in the gas monitoring data should be investigated further (e.g. where gas is detected but there is no apparent source). 

Critical areas of the site where the desk study has identified a higher risk of gas being present, for example deeper areas of landfill, the perimeter nearest an adjacent landfill site, between the gas source and a receptor, or within zones of permeable geology that could provide migration pathways... 

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