FIRE RUBBLE . . . Livermore firemen sift through the rubble of a gasoline bulk plant fire to make sure there are no more flames. Police evacuated an entile block in downtown Livermore because of about 65,000 gallons of gasoline and fuel oil in four large storage tanks (in background) only about 15 feet from the bulk plant office and storage building.—Review PhotoRichfield Oil PlantCharred Remains ProbedLIVERMORE — Firemen here •e trying — as best they can-put a building back together. The structure being “pieced gellier is the office-slorage hiding at the Richfield bulk ant at 0 Street and the South-n Pacific tracks, gutted yes-rday in a three-alarm blaze feet from 65,000 gallons ol 1 and gasoline.Sifting through ashes and charred tires, batteries and service s t ;i I i lt;j n accessories, Livermore firemen are seeking the cause of the blaze.But fire chief Jack Baird said it may be Wednesday before the detective work results in a “reason” for the fire that caused evacuation of an entire downtown block.Late yesterday even the cost of the fire hadn’t been determined, pending a liunl through inventory records by Richfield Oil Co. officials.The storage-office structure contained 50 gallon drums of oil in addition to the service slat inn accessories.“Put the contents of 20 service stations in one place and you have what burned, Baird