53 Pa. Stat. § 13643
In case the ground so selected by the council for such purposes cannot be obtained by agreement with the owner or owners at a price reasonable in the estimation of said council, or when, by reason of the absence or legal incapacity of any such owner or owners, no such price or value can be agreed upon, the city council may proceed to acquire the same by the exercise of the right of eminent domain, and the proceedings for the ascertainment of damages for such property, land or materials taken, injured or destroyed shall be in the manner and subject to the restrictions and procedure provided by the act, approved the sixteenth day of May, one thousand eight hundred and ninety-one (Pamphlet Laws, seventy-five), entitled "An act in relation to the laying out, opening, widening, straightening, extending or vacating streets and alleys, and the construction of bridges in the several municipalities of this Commonwealth, the grading, paving, macadamizing or otherwise improving streets and alleys, providing for ascertaining the damages to private property resulting therefrom, the assessment of the damages, costs and expenses thereof upon the property benefited, and the construction of sewers and payment of the damages, costs and expenses thereof, including damages to private property resulting therefrom," and the amendments and supplements thereto.
53 P.S. § 13643