What are the elements of the doctrine of equitable estoppel?

"The elements of equitable estoppel are '(1) the party to be estopped must be apprised of the facts; (2) he must intend that his conduct shall be acted upon, or must so act that the party asserting the estoppel has a right to believe it was so intended; (3) the other party must be ignorant of the true state of facts; and (4) he must rely upon the conduct to his injury.' " (Schafer v. City of Los Angeles (2015) 237 Cal.App.4th 1250, 1261.) "An additional requirement applies in cases involving equitable estoppel against the government. In such a case, the court must weigh the policy concerns to determine whether the avoidance of injustice in the particular case justifies any adverse impact on public policy or the public interest. [Citations.] Even if the four elements of equitable estoppel are satisfied, the doctrine is inapplicable if the court determines that the avoidance of injustice in the particular case does not justify the adverse impact on public policy or the public interest." (Ibid.)