California Code, Public Contract Code - PCC § 20449

Before ordering any changes made, the legislative body shall adopt a resolution briefly describing the changes proposed to be made, stating the amount of the estimated increase or decrease in the cost of the work by reason of the proposed changes and giving notice of a time and place when and where any interested person having any objection to the changes proposed to be made may appear before the legislative body and show cause why the changes should not be ordered.  The resolution shall also contain the name and telephone number of a local department or agency designated by the legislative body to answer inquiries regarding the hearing proceedings.  Such notice shall be omitted if the hearing of objections is not required as provided hereunder.  The resolution may describe the changes by referring to maps, plats, plans, profiles, detailed drawings, or specifications on file in the office of the clerk or engineer, which shall indicate the changes proposed to be made and which shall govern for all details thereof.  The resolution shall be published pursuant to Section 6061 of the Government Code, at least 10 days prior to the date of the hearing.

The hearing of objections shall not be required if the legislative body, when considering passage of the resolution, finds and determines by a four-fifth's vote of all members thereof, that all of the owners of lots or lands liable to be assessed, or their agents, who shall make oath that they are such agents, have signed and filed a petition waiving the hearing, with the clerk, on or before the fifth day prior to the day that the resolution is considered for passage, declaring that they do not have any objections to the proposed changes and requesting that the hearing of objections shall not be required.