A Washington law firm hired by Governor Carcieri's administration to help in a Tiverton pollution case has already billed the state about $448,000. And that could be just the tip of the iceberg. Regulators have proposed seeking $3.5 million more over the next year to pay for Sutherland Asbill and Brennan. The firm is helping the state in its dispute with Texas-based Southern Union Company. The state is trying to force the company to clean up toxic soil in one area town. The cleanup could cost tens millions of dollars. Critics question the spending at a time when the state is struggling financially. But Administration officials say the cost is worth it if the state wins the case.