California Code, Public Contract Code - PCC § 4104.5

(a) The officer, department, board, or commission taking bids for construction of any public work or improvement shall specify in the bid invitation and public notice the place the bids of the prime contractors are to be received and the time by which they shall be received. The date and time shall be extended by no less than 72 hours if the officer, department, board, or commission issues any material changes, additions, or deletions to the invitation later than 72 hours prior to the bid closing.Any bids received after the time specified in the notice or any extension due to material changes shall be returned unopened.

(b) As used in this section, the term “material change” means a change with a substantial cost impact on the total bid as determined by the awarding agency.

(c) As used in this section, the term “bid invitation” shall include any documents issued to prime contractors that contain descriptions of the work to be bid or the content, form, or manner of submission of bids by bidders.