Sanitation workers were trying for a second day Friday to clear a blocked sewer line that has spilled a sizable amount of raw sewage into Santa Monica Bay and has forced the closure of 6 miles of beaches, officials said.

A small amount of sewage continued to "trickle" into Ballona Creek, which leads to the bay, from the 45-inch pipeline, which was plugged Thursday, apparently by vandals who removed a sewer plate and poured an undetermined substance into the pipe, said Anna Sklar, spokeswoman for the Bureau of Sanitation.Pressure from the blockage broke a weld, from which raw sewage spilled from the pipeline leading to the Hyperion Treatment Plant.