Section 105. The jurisdiction, powers, authority and discretion delegated to the department by sections ten to twenty-six, inclusive, of this chapter and section one hundred and eighty-five of chapter one hundred and sixty shall not be limited by other provisions of law contained in chapters one hundred and fifty-nine to one hundred and sixty-three, inclusive, or in chapter one hundred and sixty-six, nor shall such provisions prevent the department from exercising to the fullest extent such jurisdiction, powers, authority and discretion.No contract shall be awarded by the authority for construction work or for the purchase of equipment supplies or materials whether for repairs or original construction, the estimated cost of which amounts to $25,000 or more, except in cases of special emergency involving the health, convenience or safety of the people using the facilities of the authority unless proposals for the same have been invited by advertisements in at least 1 newspaper circulating in each of the towns of Falmouth, Nantucket and Barnstable, the city of New Bedford and the county of Dukes county, once a week for at least 2 consecutive weeks, the last publication to be at least 1 week before the time specified for the opening of said proposals. Such advertisements shall state the time and place where plans and specifications of proposed work or supplies may be had and the time and place for opening the proposals in answer to said advertisements. Every such contract shall be awarded to the lowest responsible and eligible bidder, provided, however, the Authority may reject any such proposal if it is in the public interest. Nothing hereinbefore contained shall be construed as requiring the invitation of proposals for engineering or architectural work in connection with a proposed project.