Section 27-664. Test pits

(a) Test pits may be substituted for boring on a
  one-for-one basis. All applicable requirements as to depth,  numbers  of
  samples,  data  to  be  reported,  and  disposition  of samples shall be
  observed, except that the use of  sample  spoon,  recording  of  driving
  resistance,  and  recovery  of  rock  cores  is not required in test pit
  investigations, and except  as  provided  in  subdivision  (b)  of  this
  section.
    (b)  Test  pits for buildings not more than one story in height or for
  one or two-family residences not more than two stories  in  height  need
  only  extend  four feet below the deepest part of the excavation for the
  construction of footings, or a minimum  of  four  feet  when  foundation
  elements  rest on grade pursuant to paragraph four of subdivision (a) of
  section 27-658 of article one of this  subchapter,  provided  that  such
  structures  are  supported by footings bearing on nominally satisfactory
  bearing materials of class 9-65 (except soft clay) soil or better.