Section 27-697. Use of uncased concrete pile shafts

The use of uncased
  shafts (i.e., where the concrete of the pile shaft is in direct  contact
  with  the  surrounding  soil)  will  be  permitted  under  the following
  conditions:
    (a) For bored piles. Where the bored hole is maintained free of  water
  before and during placement of the concrete and the sides and bottom can
  be  inspected prior to such placement, and provided that no displacement
  pile shall be installed within fifteen feet of any bored pile.
    (b)  For  driven  piles  (including  all  piles  wherein  installation
  utilizes  a  temporary  casing). The maximum length of the uncased shaft
  shall  be  limited  to  ten  feet  unless  otherwise  permitted  by  the
  commissioner.    Uncased  shafts  will be permitted to be formed in soil
  below the water table but shall not be formed in any soil of class  9-65
  that  is  of medium or soft consistency; in any soil of class 10-65 that
  is of medium or loose density; or in any soil of class 11-65.