18-29-306.2.1 Overexcavation.
   Where trenches are excavated below the installation level of the pipe such that the bottom of the trench does not form the bed for the pipe, the trench shall be backfilled to the installation level of the bottom of the pipe with sand or fine gravel placed in layers of 6 inches (150 mm) maximum depth and such backfill shall be compacted after each placement.