Cal. Pub. Util. Code § 6008
Each sealed bid shall be accompanied with cash or a certified check payable to the treasurer of the county or municipality for the full amount of the bid, and no sealed bid shall be considered unless the cash or check is enclosed therewith. The successful bidder shall deposit at least 10 percent of the amount of his bid with the clerk of the county or municipality before the franchise is struck off to him. If he fails to make the deposit immediately his bid shall not be received, and is void, and the franchise shall then and there be again offered for sale to the bidder who makes the highest cash bid therefor, subject to the same conditions as to deposit. This procedure shall be had until the franchise is struck off, sold, and awarded to a bidder who makes the necessary deposit of at least 10 percent of the amount of his bid.
Ca. Pub. Util. Code § 6008