U.S. EPA Administrator Carol Browner last night said she would propose ordering General Electric to dredge PCB-contaminated hot spots along a 40-mile stretch of the upper Hudson River in New York. GE dumped large volumes of the chemicals in the river over a 30-year period, before it was against the law; it stopped doing so in 1977 when PCBs were banned. Dredging the river to remove 100,000 pounds of PCBs would cost about half a billion dollars and take about five years, the EPA said. For its part, GE contends that the Hudson is naturally cleaning itself of the pollution, burying the PCBs in sediment, and that dredging would now make the situation worse. The company filed a lawsuit last week challenging the federal Superfund law as unconstitutional, and yesterday said it would fight the dredging proposal in every way possible. The EPA will make its final decision in June, after hearing public comment on the proposal.