A new tentative four-year contract hammered out at the 11th hour between Alcoa and the United Steelworkers union includes a single health plan and a fund to help cover retiree health-care costs, and blocks a two-tier wage system -- key goals the union says it sought.

The deal also calls for automatic annual wage increases of 2.5 percent and 2 percent, respectively, for all workers over the next two years; hourly increases for most jobs the following two years; and pension increases dependent on years of service, the USW said yesterday.

Those were among the details the union highlighted a day after negotiators for both sides struck a deal two hours before a midnight deadline that could have led to a strike by 9,000 workers.

Alcoa had intended to operate the plants with management personnel if union workers had walked out. The contingent work force included several hundred employees from Pittsburgh who had been deployed to a handful of plants, spokesman Kevin Lowery said.

No date has been set for workers to vote on the tentative agreement. Until then, they will work under the previous contract. Mr. Lowery said terms of the new agreement would be retroactive to May 31, the date the old contract expired.

The deal covers workers at 15 plants in 10 states. Separately, Alcoa and about 800 USW-represented workers at a plant in Cressona, Schuylkill County, reached tentative agreement on new contract terms after more than two years of negotiations.