Section 27-710. Compacted concrete piles

(a)  Description. A "compacted
  concrete pile" shall denote a concrete pile formed with an enlarged base
  in which the concrete in the base is placed in small  batches  that  are
  compacted  prior  to attaining an initial set. The concrete in the shaft
  of the pile shall be placed as  specified  in  section  27-709  of  this
  article  for  cast-in-place  concrete  piles  if  a permanent casting is
  provided, or in small batches that are compacted.
    (b) Materials. Concrete for compacted concrete piles shall conform  to
  the  requirements  of  article  five  of subchapter ten of this chapter.
  Concrete to be compacted shall have a minimum  compressive  strength  at
  the  age  of  twenty-eight  days of four thousand psi and shall be mixed
  with sufficient water to permit hydration of the cement, but  the  slump
  shall be zero. The concrete shall be placed and compacted before initial
  set  can  occur.  Non-compacted  concrete,  if used for the pile shafts,
  shall conform to the requirements for cast-in-place concrete piles.
    (c) Spacing. Minimum spacing between compacted concrete piles shall be
  four feet six inches, center to center except that where the  shafts  of
  such  piles are cased for their full length, this spacing may be reduced
  to three feet six inches. Where a question exists as to possible  damage
  to adjacent previously driven piles, these minimums shall be increased.
    (d) Installation.
    (1)  The  base  shall  be  formed  by  ramming concrete, in batches of
  approximately five cubic feet or less, from a drive casing and into  the
  soil.  Unless  specifically  otherwise  permitted by the commissioner, a
  minimum  of  twenty  blows  of  at  least  one  hundred  forty  thousand
  foot-pounds  per  blow  shall be required for extrusion of the last five
  cubic feet of concrete. The total quantity of concrete extruded from the
  drive casing to form the base shall be equal  to  or  greater  than  the
  quantity  so  extruded  in the case of the nearest successful applicable
  test pile, except that a compactive effort in excess  of  thirty  blows,
  each of one hundred forty thousand foot-pounds, will not be required for
  extrusion of the last five cubic feet.
    (2)  After  the  expanded  base  has  been  formed, the shaft shall be
  constructed. Where a cased shaft is to be used, a steel shell  shall  be
  inserted  into  the  drive  casing  and anchored to the expanded base by
  placing a fresh charge of concrete in the shell and driving it into  the
  base.  The  shell  may then be filled with concrete to cut-off elevation
  after the removal of the drive casing, in accordance with the provisions
  relating to cast-in-place concrete piles. Any  annular  space  remaining
  between  the  shell  and  surrounding  soil  shall be suitably filled to
  assure proper lateral support of the shaft, unless there  is  sufficient
  recovery  of  the  ground  to  provide  the  necessary support. Where an
  uncased shaft is to be used, the provisions of section 27-697 of article
  seven of this subchapter shall apply, and the  concrete  for  the  shaft
  shall be placed by ramming or by the use of approved pressure devices as
  the  drive  casing  is  withdrawn.  Where  ramming is used, the concrete
  batches being rammed shall not exceed five cubic  feet  in  volume,  not
  less than two blows of thirty thousand foot-pounds each shall be applied
  to  compact  each  batch of concrete, and the bottom of the drive casing
  shall be kept below the level of the concrete at all times.
    (3) The outside diameter of the permanent shaft shall not be more than
  four inches less than the inside diameter of the drive casing.
    (4) Except where uncased shafts are  used,  as  described  in  section
  27-697  of article seven of this subchapter, no concrete shall be placed
  in the pile shafts until all piles within a radius of fifteen  feet,  or
  within the heave range, have been driven.
    (e)  Bearing  material.  The enlarged base of the pile shall be formed
  in, or on the same type of bearing material as is used  to  support  the

  nearest  applicable  load  test  pile and at a similar depth therein. In
  addition, the enlarged base shall be underlain by a minimum depth of ten
  feet (measured from  the  junction  of  the  shaft  and  base)  of  soil
  materials  of  classes  1-65 to 7-65, except that, where installation of
  the base is permitted to be performed with blows of less energy than the
  one hundred forty thousand foot-pounds indicated  in  paragraph  one  of
  subdivision (d) of this section, the requirement for a ten foot depth of
  class  1-65  to 7-65 material may be reduced, subject to the approval of
  the architect or engineer and the aproval of the commissioner.