Patent ID: 7870683

Claim:
A method for trenching below the water table in an environmentally sensitive area for placement of electric cables, water pipes, or sewer lines therein, the method using a trenching machine having a boom with a digging chain thereon, belt for moving spoil to one side, and tracks to move the trenching machine, said method including the following steps: making a first pass with said trenching machine wherein said boom is lowered and a first trench is dug with said digging chain from the surface to the water table, speed of said trenching machine being controlled by speed of said tracks and speed of said digging chain; simultaneously removing relatively dry spoil from said first trench; making a second pass in said first trench with said trenching machine with said boom lowered below said water table wherein a second trench is dug with said digging chain immediately below said first trench, a combined first and second trench retaining wet spoil therein; adjusting speed of said digging chain and said tracks during said second pass to allow said digging chain to dig effectively below said water table and prevent spillage; replacing said relatively dry spoil in said combined first and second trench; packing said relatively dry spoil and said wet spoil in said combined first and second trench; redigging packed soil from said combined first and second trench; placing said electric cables, water pipes, or sewer lines in said combined first and second trench; and refilling said combined first and second trench with suitable fill material.