In the case of such works as are necessitated due to the riparian works, where the administrative expenses of the structures which are the objects of such incidental works are payable by a private individual or a public body, the cost for such incidental works shall be borne by the party who bears the cost of riparian works, to the extent that such incidental works become necessary. However, in case a private individual or a public body receives a special benefit from such incidental works, the private individual or public body concerned may be caused to bear a part of such cost to the extent of the benefit received.