Section 318. Competitive sealed bids from prequalified vendors

In
  accordance with section three hundred seventeen, bids may  be  solicited
  from  vendors  who  have  been prequalified for the provision of a good,
  service or construction pursuant to section three hundred twenty-four by
  mailing notice to each prequalified vendor or, if special  circumstances
  require,  to  a  selected  list  of  prequalified  vendors. Award of the
  contract shall be made in accordance  with  the  provisions  of  section
  three  hundred  thirteen  of  this  chapter.  A  determination to employ
  selective solicitation for a particular procurement or for a  particular
  category  of  procurement  shall  be  made  in writing by the agency and
  approved by the mayor; unless the mayor, upon adequate assurances of  an
  agency's  capacity to comply with procedural requirements in relation to
  this section, has determined that such approval is not required  for  an
  agency's contracts or particular categories of contracts.