18-28-307.2.1.1 French drain.
   A french drain shall consist of a pit excavated in the earth not less than 24 inches (610 mm) in any dimension and completely filled with coarse gravel. The drainpipe shall extend into the pit not less than 6 inches (152 mm) below grade and shall be securely anchored in place. The drain shall not be covered with sod until inspected and approved.