Tunneling will be required when it is feasible to tunnel underneath any portion of any street or sidewalk in the City which is paved with concrete or asphalt paving. The street or sidewalk in the City which is paved with concrete and asphalt paving may be excavated as otherwise provided in this Chapter, if tunneling is not feasible after taking into consideration the location, costs, and time involved; and where a proper permit has been secured, tunnels may be driven or excavated under any such pavement provided that upon completion of the work involved the backfill shall be compacted with sand. (Prior Code, Sec. 19-20)