Upon completion of any local improvement contract and the spreading of assessments upon the property benefited thereby, all proceeds from the collection of unbonded assessments, the sale of improvement bonds, and the foreclosure of improvement liens for unbonded assessments realized from the local improvement with respect to which such general obligation improvement warrants are issued, shall be transferred from the Local Improvement District Assessment Fund created for the particular improvement and placed in the Improvement Warrant Sinking Fund in an account to be applied to the call and payment of such warrants as rapidly as funds are available as provided by statute.