5. Before commencing the construction, alteration or reconstruction of any work which will or may be situated over or within 15 metres measured in any direction of, or (wherever situated) impose any load directly upon, a relevant pipe the undertaker shall furnish to the Company such proper and sufficient plans of the work as may reasonably be required by the Company and shall not commence the work until such plans thereof have been approved in writing by the Company (which approval shall not be unreasonably withheld) or settled by arbitration under article 26.