All bids for construction work shall be presented under sealed cover and shall be accompanied by one of the following forms of bidder’s security:
(a) Cash.
(b) A cashier’s check made payable to the city.
(c) A certified check made payable to the city.
(d) A bidder’s bond executed by an admitted surety insurer, made payable to the city.
The security shall be in an amount equal to at least 10 percent of the amount of the bid. No bid shall be considered unless one of the forms of bidder’s security is enclosed with it.
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.