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Caracal Engineering Project


Project Problem

Boschendal was one of our first projects using the Caracal ground mount rack. This was not the challenge, but rather the founding technique we had to deploy in some cases around the site.

A prerequisite for the projects in which we are involved for ground mount and carport applications, is testing. Bizarrely, this seems to be an uncommon practice for many projects and seemingly growing issue. What is most puzzling, is how one would determine the embedded depth and the type of founding without undertaking these tests?


  • The soil conditions were extremely soft and, in some cases, had very large boulders below the surface. This inconsistency made the election of a single founding technique difficult.

Project Solution

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:

  1. The appropriate embedded depth considering the forces that will be acting on the table namely:
    1. Wind loads
    2. Return periods
    3. Soil conditions
    4. Risk categories
    5. Terrain categories
  2. 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:
    1. Drilling and concreting
    2. Drilling and compaction
    3. Micro-piling
    4. Hydraulic ramming
    5. other

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.