The permittee shall fill all excavations level with adjoining grade not later than ten (10) days after a building or structure is razed. Plaster, brick or other inorganic noncombustible materials may be used to fill such excavations, provided, however, the top one foot of fill shall be clean earth. The filling of such excavations shall not be required when a building permit has been issued for a new building on the site and the construction thereof is to be started within sixty (60) days after the completion of the wrecking or demolition operations. In such event, the permittee shall provide such excavation with a six foot high fence, capable of resisting lateral force of fifteen (15) pounds per square foot, to protect the excavation on all sides from pedestrian access. All debris, building material and rubbish must be removed from the property not later than ten (10) days after the building or structure is razed. (Prior code § 9.10.407)