Fortunately, Caracal employees have been involved in several hundred megawatts of ground mounted solar pv structures. The result, of course, is a deep understanding of different techniques to fix posts. Effectively Caracal has an arsenal of solutions given different ground conditions.
It is worth noting that the testing we undertake gives us vital information that gives more certainty to the project. It is often stated that you always pay for the geotechnical study, it just depends on when. We prefer to pay upfront as opposed to in the middle or the end of the project when the problems are amplified.
Our testing in involves:
- Vertical uplift tests
- Horizontal pressure tests
- Inclined traction tests
All of these result in two major findings:
- The appropriate embedded depth considering the forces that will be acting on the table namely:
- Wind loads
- Return periods
- Soil conditions
- Risk categories
- Terrain categories
- The type of founding that we would have to deploy to meet the above conditions considering the local situation of the soil. These could include:
- Drilling and concreting
- Drilling and compaction
- Hydraulic ramming
For Boschendal, post testing, we concluded that a much deeper post would be required to handle the uplift forces on the tables. The soil conditions generally were soft, so ramming was straightforward.
In some cases, we did hit impediments below the surface. We dug the posts out where they didn’t hit the minimum embedded depth informed by our testing. The boulders were too significant to break up or move, so using a bulb-shaped form we casted in the foundations and compacted around them. The bulb shape creates an interesting shape which, once buried, is exceedingly difficult to remove through the application of uplift forces.
In summary, geotechnical conditions can range on a site, so we must be nimble enough to change our solutions to deal with the context. We aren’t intimidated by this, given the number of solutions we have had to deploy over the years.