Geotechnical survey for Family Home

Black and white photo of four mean operating a drilling device — Photo: Alfred Quartey

We hired a geotechnical engineer to conduct a geotechnical survey on our plot, partly because it’s best practice to do so before you begin construction, but also because we’re considering doing a basement level, and we need to understand what’s below the surface before we make a final decision.

The purpose of the investigation was to evaluate subsurface soil and geologic conditions underlying the site, and then based on what was found, the engineer would make recommendations on the geotechnical aspects of the proposed design and construction.

Black and white photo of one of the boreholes — Each borehole was between 6 to 8 meters deep. Photo: Alfred Quartey

Two men operating the drilling machine — Photo: Alfred Quartey

Two men opreating the drilling machine — Photo: Alfred Quartey

The scope of work included a site reconnaissance, desk study, field exploration (involving sinking of boreholes, soil sampling, and performance of in-situ test) and laboratory testing, and concluded in a written report.

Wide landscape photo of the drilling machine and its operators. Low mountains loom in the background. — Photo: Alfred Quartey

Three men operating the drilling machine — Photo: Alfred Quartey

One man holds up a shovel full of soil and another appears to be breaking it between his fingers, testing for something — Photo: Alfred Quartey

Workers assembling the drilling machine — Photo: Alfred Quartey

This was the first “earth moving” on the site, so my brother Alfred was there to capture the moment. I love having a professional photographer in the family.

Close-up of the drilling machines cables — Photo: Alfred Quartey

Two men setting up cables — Photo: Alfred Quartey

A man in a helmet and bright reflective vest takes a brief break — Photo: Alfred Quartey

The drilling itself took only a few hours, and we received the full report about a week and a half later.

I was pleasantly surprised at how comprehensive it was. It included information about the nature and condition of the subsoil, information about the water table, the soil chemistry, recommendations for how we should approach the foundation, and more.

Screenshot of table of contents. Main sections are introduction, site descrition, detail of the geotechnical investigation, findings from the results of the investigation, foundations design consideration - recommendations, summary and conclusions, and appendix — Tabe of contents of the report

Screenshot of the borehole record. It's a table showing what was discovered at each depth that the borehole was lowered — Details of one of the boreholes

The section about the seismicity of the area (how likely it is to experience an earthquake, and how it might behave in such a scenario) was especially interesting.

Screenshot of the section talking about seismicity. Basically says that the site is not near any major fault line, and in the unlikely event of seismic activity, the soil type has shown to result in little damage — Seismicity of the area

Here is the summary of the report.

Summary page says there is no geological instability, that soil is mostly quartz schist, that groundwater was not encountered, and gives recommendation for type of foundation

The name of the geotechnical firm we used is Geoconsultants. We had a good experience, and I’m happy to recommend them. You can reach founder Steve Pinkrah at +233208243464. Feel free to mention that you were referred by Emmanuel’s article.

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Jul 3, 2021 - Accra, Ghana

Tagged: architecture, appolonia city