If the structural engineer prescribes a scope of work (number of borings, locations, depths) and some geotechnical abnormality or failure occurs, you (the structural) engineer will share in the liability. It's best to define the structural engineering objective that you need (i.e., foundation support, lateral earth pressures, site preparation and grading recommendations, etc.) and let the geotechnical engineer determine the appropriate field and laboratory program to accomplish the goal - whether that means 5 borings and 10 lab tests or 45 borings and 100 lab tests.
Just a few thoughts on the matter. . .
f-d
¡papá gordo ain’t no madre flaca!