Section 17-147. Execution

If  such  order is not complied with, or so far
  complied with as the board may regard as reasonable,  within  five  days
  after service or attempted service or within any shorter time, which, in
  case  of  imminent  peril  to  the  public  health,  the  board may have
  designated, or is not thereafter speedily and fully executed, then  such
  order  may  be executed as any of the orders of the board or department.
  Any agency of the city is authorized to act as agent of  the  department
  in  executing  such order. In the event that any agency shall so act, it
  shall certify and  transmit  to  the  department  its  expenses  in  the
  execution  of  such order separately in respect of each separately owned
  parcel of property. Such expenses shall be reimbursed to such agency and
  shall be chargeable and collectible as expenses  of  the  department  in
  connection  with  the  execution  of  an  order  as  referred to in this
  chapter.