PCC §20405: (a) The board shall afford all bidders an opportunity to examine the plans, specifications, and working details, and shall award the contract to the lowest responsible bidder.

(a) The board shall afford all bidders an opportunity to examine the plans, specifications, and working details, and shall award the contract to the lowest responsible bidder. The board may provide by resolution that the bids be opened, examined, and declared by an officer designated in the resolution. The resolution shall require that the bids be opened at a public meeting called by the officer and that the results of the bidding be reported to the board at a subsequent regular board meeting. The notice inviting bids shall state the time and place of the public meeting and the name of the designated officer. (b) 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: (1) Cash. (2) A cashier’s check made payable to the county. (3) A certified check made payable to the county. (4) A bidder’s bond executed by an admitted surety insurer, made payable to the county. 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 county beyond 60 days from the time the award is made. (c) The person to whom the contract is awarded shall execute a bond, approved by the board, for the faithful performance of the contract. The person shall perform the work in accordance with the plans, specifications, and working details, unless all or any of them are modified by a four-fifths vote of the members of the board. In that case, if the cost of the work is reduced by reason of the modification, the person to whom the contract is awarded shall make an allowance on the contract price to the extent of the reduction. (d) In any county that has appointed a road commissioner pursuant to Section 2006 of the Streets and Highways Code, or in any county that has abolished the office of road commissioner and complied with Section 2006.1 of the Streets and Highways Code, the board may authorize the road commissioner, or a registered civil engineer under the direction of the county director of transportation, to execute changes or additions to the work for any contract made pursuant to this article in an amount not to exceed: (1) For contracts whose original cost is less than fifty thousand dollars ($50,000), the amount of the change or addition shall not exceed five thousand dollars ($5,000). (2) For contracts whose original cost is fifty thousand dollars ($50,000), but less than two hundred fifty thousand dollars ($250,000), the amount of the change or addition shall not exceed 10 percent of the amount of the cost of the original contract. (3) For contracts whose original cost exceeds two hundred fifty thousand dollars ($250,000), the extra cost for any change or addition to the work so ordered shall not exceed twenty-five thousand dollars ($25,000), plus 5 percent of the amount of the cost of the original contract that is in excess of two hundred fifty thousand dollars ($250,000). In no event shall any change or addition exceed two hundred ten thousand dollars ($210,000). (e) This section shall become operative on January 1, 2027.