Such enlarged sanitary drainage district shall have power to defray the expenses of any improvement made by it and to defray the expenses of carrying into execution the powers hereby granted by general taxation or by special assessment or partly by special assessment and partly by general taxation as the trustees may by order determine. It shall constitute no defense to any tax or special assessment that the improvements for which the same is imposed lies partly or wholly outside the limits of such district. No property shall be assessed more than it is benefited by the improvement for which the assessment is levied. The proceedings for apportioning the benefits and imposing a special assessment by the trustees of such enlarged district shall be the same as those for apportioning benefits and levying of special assessments in sanitary drainage districts organized under sections 31-401 to 31-449.