Cal. Public Contract Code - PCC § 20929. Section 20929.
All bids for construction work requested by an agency or district covered by this chapter 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 agency or district.
(c)
A certified check made payable to the agency or district.
(d)
A bidder’s bond executed by an admitted surety insurer, made payable to the agency or district.
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 agency or district beyond 60 days from the time the award is made.