N.Y.C. Admin. Code § 19-143: § 19-143 Excavations for public works.

a. Notice to public service corporations. Whenever any street shall be regulated or graded, in which the pipes, mains or conduits of public service corporations are laid, the contractor therefor shall give notice thereof in writing to such corporations, at least forty-eight hours before breaking ground therefor. Such provision shall be included in every contract for regulating or grading any street in which the pipes, mains or conduits of public service corporations shall be laid at the time of making such contract.

b. Public service corporations shall protect their property. Public service corporations whose pipes, mains or conduits are about to be disturbed by the regulating or grading of any street, shall, on the receipt of the notice provided for in the preceding subdivision, remove or otherwise protect and replace their pipes, mains and conduits, and all fixtures and appliances connected therewith or attached thereto, where necessary, under the direction of the commissioner.