In Warner Constr. Corp. v. City of Los Angeles (1970) 2 Cal.3d 285, the plaintiff brought an action against the City for a balance due on a contract for construction of a retaining wall including delay damages, among other things. There, unlike here, the City's liability was put directly in issue. in February 1965 the plaintiff notified the City of its unwillingness to continue work without a change order to permit drilling with rotary mud, a special drilling fluid, after cave-ins occurred due to the sandy nature of the hillside. On March 8, the City directed the plaintiff to resume work without a change order. On March 19, the plaintiff submitted a request for a change order of $ 12,000. The City authorized the use of the rotary mud for a cost of $ 12,000, but after the plaintiff notified the City that the cost would actually be $ 34,400, the City did not issue the change order. The California Supreme Court determined that a dispute had arisen by March 8 on the crucial question of whether the plaintiff would be entitled to a change order, and negotiations after that date were subject to exclusion under section 1152. The court rejected the plaintiff's contention that the correspondence could have been admitted to show the contemporaneous and practical construction of the contract. ( Id. at p. 296.) However, the court found that the correspondence between the parties could have been admitted to show that the plaintiff had engaged in negotiations in good faith and pursuant to the contract procedure in the reasonable hope that an agreement could be reached.