N.Y. Comp. Codes R. & Regs. tit. 16, § 255.361 – Service lines: installation.

(a) Each buried service line shall be installed with at least 18 inches (457 millimeters) of cover. However, where an underground structure prevents installation at those depths, the service line must be able to withstand any anticipated external load and suitable protection must be provided. Also, if service inserts of existing service lines are installed this requirement is not applicable.
(b) Each service line must be properly supported on undisturbed or well-compacted soil, and material used for backfill must be free of materials that could damage the pipe or its coating.
(c) Where condensate in the gas might cause interruption in the gas supply to the customer, the service line must be graded so as to drain into the main or into drips at the low points in the service line.
(d) Each service line must be installed so as to minimize anticipated piping strain and external loading.
(e) Each underground service line installed below grade through the outer foundation wall of a building must:
1. (1) be encased in a rigid sleeve with suitable protection from shearing action or backfill settlement;
2. (2) in the case of a metal service line, be protected against corrosion; and
3. (3) be sealed at the foundation wall to prevent leakage into the building.
(f) When an underground service line is installed under a building, the following requirements apply:
1. (1) It must be encased in a gas-tight conduit.
2. (2) The conduit and the service line must, if the service line supplies the building it underlies, extend into a normally usable and accessible part of the building.
3. (3) The space between the conduit and the service line must be sealed to prevent gas leakage into the building and, if the conduit is sealed at both ends, a vent line from the annular space must extend to a point where gas would not be a hazard, and extend above grade, terminating in a rain and insect resistant fitting.
(g) All service lines shall be constructed with a clearance of not less than four inches (102 millimeters), whenever practical, from any subsurface structures not directly associated with the pipeline. If it is not practicable to achieve this clearance, a minimum clearance of two inches (51 millimeters) shall be maintained and the pipeline shall be protected from damage that might result from the proximity of the other structure.
(h) When steel or plastic pipe is to be installed as a service line in a bore, care shall be exercised to prevent damage to the coating or pipe during installation.
(i) Locating underground service lines.
Each underground nonmetallic service line that is not encased must have a means of locating the pipe that complies with section 255.321(e) of this Part.