Marathon Petroleum provides update on Garyville refinery operations Marathon Petroleum Corporation's Garyville refinery was impacted by a tornado that occurred on May 28. As a result of this severe weather, the refinery experienced damage to a cooling water system that serves part of the refinery causing the No. 1 crude unit and other units to be taken off-line. Based on MPC's initial assessment of the damage and necessary repairs, the crude unit is anticipated to be operational by mid-June. The company does not expect total refinery throughputs to be significantly impacted, projecting less than a 5% reduction to the company's prior throughput guidance for this quarter.