Drainrock, $300 for a 360 sq ft (typical 3 bedroom) drainfield plus $250 for delivery (depending on distance from the pit regardless of who is driving the dump truck.) You must include the cost of digging out the drainfield area, placing and shoveling rock and placing and assembling the perforated pipes (this is mostly equipment and shovel time.) Some rock is lost by all good excavators who leave