The provisions of this subheading shall be deemed to provide an additional and alternative method for the doings of the things authorized hereby and shall be regarded as supplemental and additional to powers conferred by other laws and shall, except as provided in Section 15 <em>{sic} </em>hereof, not be regarded as in derogation of any powers now existing, and such provisions shall be liberally construed to effect the purposes thereof. P.L.L., 1969, §10-14 1945, ch. 863