Section 27-687. Construction of footings, foundation piers, and foundation walls

The provisions of sections 27-661 and 27-723 of  this  subchapter  shall apply. In addition, methods of installation and construction shall
  satisfy the following conditions:
    (a)  Footings, piers, or walls shall be founded on undisturbed soil or
  on satisfactorily compacted or prepared materials.
    (b) Accurate preparation  and  inspection  of  the  bearing  materials
  directly  underlying  the  foundation shall be possible; and the bearing
  area shall be substantially level or suitably benched.
    (c) Excavation shall  be  kept  substantially  free  of  water  during
  construction  of the foundation except that the use of tremie or similar
  underwater construction will be permitted in  the  case  of  foundations
  bearing  directly on rock, provided that the construction procedure will
  permit thorough cleaning and preparation of the rock surface,  and  that
  the  surface of the rock is maintained in a clean condition, unfouled by
  the inflow of soil or settlement of  the  fluid  suspension,  until  the
  concrete is in place.