1. A sonic pile driving adapter, comprising:an upper attachment portion for selectively attaching the adapter to a drill head;
a lower mounting portion including at least first and second side plates configured to be inserted into a member to be sonically pile driven, wherein the first and second side plates include a first plurality of through holes corresponding to a second plurality of through holes provided on the member;
a plurality of brackets including a third plurality of through holes positioned for alignment with corresponding through holes of the first and second pluralities of through holes, the brackets configured to be positioned on an outside surface of the member to sandwich a portion of the member between at least one of the brackets and at least one of the first and second side plates; and
a plurality of fasteners that extend through the first, second, and third pluralities of through holes for coupling the sonic pile driving adapter to the member.