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Southwest Environmental Limited
Suite 2201, 250 Yonge Street, Toronto, Ontario , Canada M5B 2L7

Phone: 647 794 0233             Email: swenviro+toronto@gmail.com

Environmental Consultancy Services to Industry, Business and Individuals

Geotechnical Consultants

Desktop Study (Initial Study)

A desktop study is the first step in the geotechnical investigation process. Use of secondary data can help inform choices as to whether a site investigation is required. In its most basic form a desktop study might be considered in part of the tendering process for a site investigation, viewing of geological maps or historic borehole records is vital when choosing the correct equipment, for advancing bore holes.

Secondary data can also throw up risk ratings around issues such as subsidence of shrink swell, and this will dictated whether a site investigation is required or not. For example a high shrink swell risk (plasticity) would lead to the inclusion of plasticity index testing in the site investigation, whilst a low risk (gravels for example) may indicate these tests are not required.

British Columbia for example give the following guidance:

If an Initial Study Is Needed...

If there is no existing study of the area but one is required, the District Development Technician, at the direction of the Approving Officer, sends the applicant a letter asking for an initial geotechnical study.

If a Site-Specific Study Is Needed...

If a blanket study of the area has been done and shows evidence of natural hazards, the District Development Technician, at the direction of the Approving Officer, sends the applicant a letter of preliminary non-approval suggesting that a qualified Professional Engineer be hired to do a site-specific study. If the blanket study is a public document, it should be referred to in the letter.

Outcome of the Study

After receiving the letter from the District Development Technician, the applicant may engage a qualified Professional Engineer to do a geotechnical study of the site. Its goals would be to: Determine if there is a hazard Determine extent of any hazard Identify building sites free from hazard, or where risk could be rendered acceptable

Geotechnical Site Investigation

A site investigation is the "practical" part of the process, with primary data collection being the main goal. A drilling rig is typically used to collect soil samples and to take samples. An excavator is sometimes uses instead of a drilling rig, or in addition to a drilling rig to form trial pits, that may be observed for various geotechnical features.

Broadly a site investigation can be split in to two camps:

Site Investigation for Rocks

Geotechnical Site Investigation is rock are typically more costly than those carried out in soils. This is because of the equipment required, and in some cases the relatively slow rate of progress.

Site Investigation for Soils

Soil is typically soft than rock (although not always) and so this means that smaller drilling rigs can be used and progress is quicker.

Foundation Design

Data from the labs and from in-situ testing is used to design foundations. For simple structures it may be appropriate to use basic loads bearing calculations, but for larger projects modeling may be required.

Please contact SWEL if you would like us to undertake a Geotechnical Assessment of your Site.