Photo of the Calcutta Docks taken in 1893 by an unknown photographer showing dredging operations in progress . The Calcutta Port is the only major riverine port in India and constitutes the Calcutta Dock System. In March 1884, the Secretary of State confirmed Kidderpore as the site for construction of new docks. Dock number one, the outer dock, was primarily intended for vessels bringing imports and loading export cargoes. The temporary railway lines were constructed for the easy removal of 'spoil', or waste earth accumulated during the excavation of the site.Source: bl.uk