10.  Every such work shall be carried out under the supervision of the Director-General of Public Works, or such officer of his Department as he may appoint, and the cost of the construction of every work carried out under this Act shall in the first instance be charged on and paid out of the Consolidated Fund and shall, together with interest at the rate of 6% per annum, be payable by the proprietors of the lands benefited in the manner hereinafter provided.