N.Y.C. Admin. Code § 27-687: § 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.