CHARLESTON, W.Va. — A revised class-action settlement plan is back before a federal judge deciding how to pay victims of a chemical spill that left people without tap water for up to 9 days.

The drinking water of about 300,000 people in the greater Charleston area was contaminated in January 2014 when a chemical used to clean coal spilled from a storage tank at the now-defunct Freedom Industries, polluting the Elk River upstream from the system’s water intake.

Judge John Copenhaver raised concerns about previous terms of the negotiated $151 million settlement with West Virginia American Water Co. and Eastman Chemical. This amended plan replaces tiered and fixed amounts with percentages and cost-based factors for businesses and medical claims.

It would raise payment for a simple household claim from $525 to $550.