Section 1621-G. Construction and purchase contracts

The authority shall let
  contracts for construction in the same manner, so far as practicable, as
  is  provided  by  law  for contracts for the city, except that where the
  estimated expense of a contract does not exceed  five  thousand  dollars
  such  contract  may  be  entered into without public letting. Nothing in
  this section shall be construed to limit the power of the  authority  to
  do  any  construction  directly by the officers, agents and employees of
  the authority. Contracts for the purchase  of  supplies,  materials  and
  equipment  shall  be  let  in  the same manner as is provided by law for
  contracts of the city.