In Ortega v. Pajaro Valley Unified School Dist. (1998) 64 Cal.App.4th 1023, the court analyzed the doctrine of estoppel as it applies to public entities. " 'Generally speaking, four elements must be present in order to apply the doctrine of equitable estoppel: (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 had a right to believe it was so intended; (3) the other party must be ignorant of the true state of facts; (4) he must rely upon the conduct to his injury. ' " ( Id. at p. 1044.) As Ortega explains, " 'estoppel most commonly results from misleading statements about the need for or advisability of a claim; actual fraud or the intent to mislead is not essential.' " (Ortega, at p. 1044.) But Ortega further points out that estoppel is not dependent on the making of promises or representations; it could arise from other factual circumstances showing the public entity acted in an " 'unconscionable' manner or tried to take 'unfair advantage' of the plaintiff, taking into account the totality of the circumstances." ( Id. at p. 1044, fn. 14.) The relevant factors to be considered in this situation include " 'whether or not the inaccurate advice or information is negligently ascertained, whether or to what extent the agency is certain of the information it dispenses, whether the agency purports to advise and direct or merely to inform and respond to inquiries, whether the agency acts in bad faith, whether the claimant is one who purports to have no knowledge or training which would aid him in determining his rights and the public agency purports to be informed and knowledgeable, whether the right of which claimant is being deprived is significant, and whether a confidential relationship exists between the claimant and the public entity.' " (Ibid.) Finally, the Ortega court observed that claims of estoppel have been rejected where the plaintiff cannot show calculated conduct or representations by the public entity or its agents that induced the plaintiff to remain inactive and not to comply with the claims-presentation requirements. (Ortega, supra, 64 Cal.App.4th at pp. 1044-1045.)