A dozen oil companies agreed to pay $423 million in cash plus clean-up costs to settle litigation over groundwater contamination from the gasoline additive, MTBE, lawyers representing public water utilities and public agencies in 17 states, told Reuters. The settlement, filed in the US District Court in Manhattan, involves BP America Inc, Chevron Corp, ConocoPhillips, Shell Oil Co, Marathon Oil Corp, Venezuela's Citgo Petroleum Corp, Sunoco Inc and Valero Energy Corp, the newspaper said.