Hanson Industries, Iselin, N.J., has split its $2 billion defined benefit plan into three following the breakup of the company. Changes in investment management are expected early next year, said Bill Lavoy, director of pension management. Hanson Industries' former plan has been divided into one each for Hanson North America, Millenium Holdings and Peabody Holdings. Peabody hired Hewitt as its consultant; the other two plans kept Evaluation Associates, Hanson's consultant. Mr. Lavoy wouldn't specify how much in assets each plan will have. He said changes in money managers will not need to be made right away.