Section 27-680. Utility services

Where utility service lines are to be laid
  in soil materials of class 11-65, provision shall  be  made  to  prevent
  damage to such service lines as follows:
    (a)  Where  the  lines  enter  a  structure,  including  a building, a
  manhole, or a junction chamber, that is rigidly supported on piles or in
  firm bearing material, the services  shall  be  supported  on  piles  or
  bearing   materials   of   adequate  firmness  to  prevent  differential
  settlement  of  the  service  lines  with  respect  to  the   structure;
  otherwise,  provisions, such as oversized sleeves, flexible connections,
  utility tunnels, or other approved device, shall be made to  permit  the
  anticipated differential movement to occur without damage to the service
  lines.
    (b)  Where  the  lines  enter  a  structure  that is supported on soil
  materials of class 11-65 or on soft clay or  loose  silt  deposits,  and
  engineering   analysis  shall  be  made  of  the  probable  differential
  settlement of the utility service line with respect  to  the  structure,
  and  provision  shall  be  made  to  accommodate  such  displacement, as
  described in subdivision (a) of this section.