Key utilities may be repaired and running on Tuesday clearing the path for BP Plc (BP.L) to begin restarting the largest refinery in the U.S. Midwest by Wednesday, said sources familiar with plant operations.

An Aug. 24 electrical fire shut units and cut power to the cooling water system, temporarily idling the 435,000 barrel-per-day (bpd) Whiting, Indiana, refinery as fall harvest season begins.

Federal and state agencies have moved to ease restrictions on selling winter-grade gasoline and on trucking hours to central plains states since the fire.

"The team is working diligently to bring back refinery operations in the coming days," BP spokesperson Christina Audisho said in an emailed statement on Tuesday.

BP called in almost all of the refinery’s employees to work on restoring production.

Motor fuel prices continued to rise in the Chicago market on Monday due to uncertainty over the status of the Whiting refinery, traders said.

Chicago CBOB gasoline has climbed since the Aug. 24 fire, traders said.

Because of the Whiting shutdown, the U.S. Environmental Protection Agency waived through Sept. 15 federal regulations for use of winter-grade gasoline, which can cause ground-level smog formation in high summer temperatures, on the fuel sold in Illinois, Indiana, Michigan, and Wisconsin, to facilitate the supply of fuel.

The U.S. Transportation Department has waived restrictions on the number of hours truckers may drive to those four states to facilitate the tankers delivering gasoline.

The governors in Michigan, Wisconsin, Indiana and Illinois have also waived state rules on using winter-grade gasoline, according to statements issued by their offices.

“This coordinated effort with our neighboring states will reduce the chance of disruptions and keep the people and businesses of Illinois moving,” said Illinois Governor J.B. Pritzker.