The Oakland Unified School District has settled a week-long strike with its teachers union — a deal that will boost pay a total of $70 million. But as the administration figures out how to pay for those raises, could it also face stiff fines for the time its 34,000 students went without teachers? District officials had no answers early this week, but the experience of another large Northern California school district’s lengthy strike last year is sobering: The Sacramento City Unified School District expects to be hit with a hefty $47 million in penalties after a two-week strike left it short of the state’s required 180-day instruction time. “It’s significant,” said Brian Heap, Sacramento City Unified’s chief communications officer. “It’s not a small amount of money.” At Oakland Unified, eight days of regular classes were lost, and although campuses were not officially closed, teachers were absent, and the few students who showed up were supervised by administrative staff. The Oakland Education Association, representing nearly 3,000 K-12 teachers, counselors, psychologists, social workers, speech pathologists, nurses, librarians and teacher substitutes, declined to comment. The district did not