Just as construction projects start from the ground up — so does the project design. Doing the soil work first, in the form of a geotechnical site evaluation, is a sensible first step to take for a successful design. A qualified geotechnical engineer should be one of the first “boots on the ground” design professionals to observe, assess and investigate the site.
It is the job of the geotechnical engineer to look at the building location and entire building system to make sure it is consistent with the architect’s vision, and the owner’s needs and financial capacity. This includes understanding and investigating — the purpose and use of the building, probable service-life loading, framing type, construction methods, soil profile, the setting, and topography for possible land restrictions, constraints or potential geologic hazards.
After these items are defined and the soil investigation results are known, the geotechnical engineer will compile all of these results into a report and communicate with the other members of the design team, typically the architect and civil/structural engineers.
A qualified geotechnical engineer will be able to communicate design parameters and restrictions with the design professionals. They will be able to make modifications and adjustments along the way as the design evolves to collectively meet the “sweet spot”, where beauty, buildability and budget all meet in the middle.
For instance, if the geotechnical engineer recommends unnecessarily low soil bearing pressures in an effort to be ultra-conservative, that will most likely result in the design of more expensive foundations. On the flip side, if a geotechnical evaluation is not performed or the recommendations are not conservative enough, it may result in a cheaper yet risky design. A qualified geotechnical engineer will be able to provide safe design parameters and recommendations as the design progresses.
So what does all this cost? A typical geotechnical site investigation is typically 0.15 to 0.3% of the overall construction cost. It is a small price to pay to uncover a myriad of potential difficulties that occur during construction and can vary from on-site soils workability and suitability to site safety trench shoring and slope stability issues. The bottom line is that a geotechnical site evaluations performed by a qualified engineer at the beginning of a project will get your “groundwork” off on the right foot!
