As soon as practicable after the adoption of the first policy plan by the council as provided in section 473.146, and before undertaking the construction of any extensions or additions to its disposal system or the substantial alteration or improvement of its existing disposal system, each local government unit shall adopt a similar policy plan for the collection, treatment and disposal of sewage for which the local government unit is responsible, coordinated with the council’s plan, and may revise the same as often as it deems necessary. Each such plan shall be submitted forthwith to the council for review and shall be subject to the approval of the council as to those features affecting the council’s responsibilities as determined by the council. Any such features disapproved by the council shall be modified in accordance with the council’s recommendations. No construction of new sewers or other disposal facilities, and no substantial alteration or improvement of any existing sewers or other disposal facilities involving such features, shall be undertaken by any local government unit unless its governing body shall first find the same to be in accordance with its comprehensive plan and program as approved by the council. At the time each local government unit makes application to the Minnesota Pollution Control Agency for a permit to alter or improve its disposal system it shall file with the council a copy of the application together with design data and a location map of the project.