53 Pa. Stat. § 53408
Whenever, after the passage of this act, the council of any borough, or incorporated town in this Commonwealth shall, by ordinance, authorize the construction, or building, or acquisition of any sewer or system of sewers; the grading, the sub-grading, or the permanent paving and improvement of any streets, avenues, alleys, courts, or any highways or parts thereof, in said borough or incorporated town; and the entire cost, or any part of the costs, of the said improvement, shall be assessed against the properties fronting and abutting on and along said improvement, whether by the foot-front rule or according to benefits; it shall be lawful for the council of the said boroughs or incorporated towns to provide, in said ordinance, that the said assessments may be paid in semiannual or annual instalments, which instalments shall bear interest at a rate not exceeding six (6) per centum, from the date of the commencement of the work or construction of the said improvement, until paid; and in order to provide for the payment of the cost and expense of such improvement as it progresses, the council of said borough or incorporated town may, from time to time, issue bonds in such sums as may be required, in all to an amount not exceeding the amount of said assessments. Said bonds shall bear the name of the sewer system built, or the name of the street, avenue, or alley, or part thereof, to be improved, and shall rest alone for their security and payment upon the said assessments; and shall be payable at periods not exceeding five (5) years from the date of their issue, to be provided in the ordinance directing the improvement; and shall bear interest at a rate not exceeding six (6) per centum per annum, payable semiannually or annually, as the council in said ordinance shall direct. Said bonds shall be negotiated at not less than par, and the proceeds thereof applied solely to the payment of the costs of said improvement. In case the said bonds are not negotiated by the council, they may be delivered to the contractor in payment of the work, but when so delivered must be at their par value.
53 P.S. § 53408