California Code, Streets and Highways Code - SHC § 8780

At the time set for the hearing the legislative body shall proceed to hear any person appearing and may determine whether or not such deficiency was due to the fact that the original assessment for such cost and incidental expenses was not apportioned equitably or in accordance with benefits. The hearing may be postponed from time to time. If it appears to the legislative body that the amount apportioned to any lot was less than the amount which such lot should equitably bear according to the benefit which it received from the improvement, the legislative body may levy a supplemental assessment apportioning to such lot the additional sums which it should equitably bear according to such benefits.