73 Pa. Stat. § 1602
A bidder to any construction contract for the construction, reconstruction, demolition, alteration or repair of any public building or other public improvement or for the provision of services to or lease of real or personal property whether by lease or concession from such contracting body, excepting highway work, may withdraw his bid from consideration after the bid opening without forfeiture of the certified check, bank cashier's check, surety bid bond or other security filed with the bid if the price bid was submitted in good faith, and the bidder submits credible evidence that the reason for the price bid being substantially lower was a clerical mistake as opposed to a judgment mistake, and was actually due to an unintentional and substantial arithmetical error or an unintentional omission of a substantial quantity of work, labor, material or services made directly in the compilation of the bid; provided, (i) notice of a claim of the right to withdraw such bid is made in writing with the contracting body within two business days after the opening of bids; and (ii) the withdrawal of the bid would not result in the awarding of the contract on another bid of the same bidder, his partner, or to a corporation or business venture owned by or in which he has a substantial interest. No bidder who is permitted to withdraw a bid shall supply any material or labor to, or perform any subcontract or other work agreement for any person to whom a contract or subcontract is awarded in the performance of the contract for which the withdrawn bid was submitted, without the written approval of the contracting body. The contracting body may prepare regulations to carry out the intent and purposes of the act.
73 P.S. § 1602