The security shall be forfeited to the city in case the bidder depositing it does not, within 15 days after the notice that the contract has been awarded to him or her, enter into a contract with the city for making the improvement, the faithful performance of which shall be secured by an undertaking in those penal sums as the city council shall require, with sureties satisfactory to that body. In any case where competitive bidding is required, the contract shall be awarded to the lowest responsible bidder. Upon an award to the lowest bidder, the security of an unsuccessful bidder shall be returned in a reasonable period of time, but in no event shall that security be held by the city beyond 60 days from the time the award is made.
Ca. Pub. Cont. Code § 20501