The use of land for the removal of topsoil, sand, gravel or other material from the land is not permitted in any district, except under a temporary certificate from the Building Inspector issued upon approval of the Plan Commission and on condition that such removal of soil will not be below the normal building grade as established from the nearest existing or proposed street when such building grade has been established and approved by the City's consulting engineer. A temporary certificate may be issued in appropriate cases upon the filing of an application accompanied by a suitable agreement or bond that such removal will not cause stagnant water to collect or leave the surface of the land at the expiration of such permit in an unstable condition or unfit for the growing of turf or for other land uses permitted in the district in which such removal occurs. This regulation shall not prohibit the normal removal of soil for the construction of an approved building or structure when such plans have been approved by the Building Inspector and a building permit has been issued and a contract let for such building development.