It seems that "Site Improvement cost" is not taken into account in the Total Direct cost. The following image is an example of how forcing he rest of the direct cost variables to 0, total direct cost is 0 when site improvement cost is not. 
It seems that "Site Improvement cost" is not taken into account in the Total Direct cost.
The following image is an example of how forcing he rest of the direct cost variables to 0, total direct cost is 0 when site improvement cost is not.
