Upon receipt of the application the commission shall cause an investigation to be made by its executive engineer or other engineers or other competent persons in its employ, or in the employ of other departments of the State, of the matters set forth in the petition, including the plans and specifications. A copy of the application shall be submitted by the commission to the Superintendent of Public Works for his approval, disapproval or other recommendations. Upon completion of such investigation, the person conducting the same shall make a report in writing to the commission recommending either his approval of the project as submitted or with modifications, or his disapproval.