Instead of digging a deep ditch we decided to brick up the foundation.  This has two advantages. First, you have no problem with  surface water (Rainwater), second you can simply equalize the found topography. The newly formed foundation was filled with non freeze material as 0/45mm gravel. At the top we build a concrete slab as you can see below:

Before concreting the pier, we installed the pier adapter. After that, we finished the Pier.

Now it was time to build the two footing foundations for the  vertical roof support, as you can see here:

Now, all the needed foundation work is done. So it is time to build the roll-off roof itself. If you are interested in it, please take a look at Part II...