My contract calls for the installation of "bit night geo-grout" in the well holes for my vertical, closed loop system. Today, the contractor indicated that the well driller he works with may not be able to get his grout rig up to my house. As an alternative, he mentioned the use of granite pea gravel as the grout, since he knows he will be able to get a dump truck to my house carrying pea gravel. I'm wondering how granite pea gravel will perform as a substitute for geo-grout? Will the installation be any less efficient using gravel? Is there anything else I should know about this possible switch?