Five major oil refineries in the San Francisco Bay Area will be fined for failing to take adequate steps to guard against spills, the federal Environmental Protection Agency said. The facilities were inspected by the EPA after a large oil leak at the Shell refinery in Martinez last April. Keith Takata, deputy director of the EPA’s water management division, said the fines could amount to $5,000 per violation for each day the law was broken. The inspections were in July and August after Shell spilled 400,000 gallons of crude oil into Martinez Wetlands and Suisun and San Pablo bays. “The potential is there for future spills,” Takata said of the five refineries. He identified them as Chevron in Richmond, Exxon Co. in Benicia, Pacific Refining Co. in Hercules, Tosco Corp. in Martinez and Unocal Corp. in Rodeo.