Marathon Pipe Line LLC & Ohio River Pipe Line LLC Announce an Extension of the Binding Open Season for the Cornerstone Pipeline and Utica Build-Out Projects

FINDLAY, Ohio, Mar. 13, 2015 - Marathon Pipe Line LLC (MPL) and Ohio River Pipe Line LLC (ORPL), subsidiaries of MPLX LP (NYSE: MPLX), today jointly announced an extension of the binding open season on the Cornerstone Pipeline and other associated Utica Shale build-out projects in order to allow additional time to discuss opportunities and address the needs of all interested shippers.  The binding open season, which was originally scheduled to conclude at noon EST on March 13, 2015, will be extended to April 13, 2015 at noon EDT.

Due to significant interest in the Cornerstone Pipeline and Utica Build-Out Projects thus far, MPL and ORPL are extending the open season to finalize transportation service agreements.

About the Cornerstone Pipeline
As previously announced, the proposed Cornerstone Pipeline will originate in Harrison County, Ohio and deliver to Marathon Petroleum Company LP's (MPC) Canton, Ohio refinery and to ORPL's East Sparta, Ohio tank farm.  The Cornerstone Pipeline is being designed as a 16" diameter pipeline system that will be routed to provide the opportunity for connections to various Utica Shale condensate stabilization facilities, fractionator facilities, cryogenic facilities, along with potential future gathering and storage facilities.  The Cornerstone Pipeline will be a batched system with the ability to transport condensate, natural gasoline, diluent and butane.  The estimated in-service date for the Cornerstone Pipeline is anticipated to be late 2016.

About the Utica Build-Out Projects
MPL, as operator of ORPL, is also advancing various Utica Build-Out Projects to provide service to additional markets beyond Canton, Ohio.  The Cornerstone Pipeline will deliver volumes into the East Sparta tank farm for transportation to additional markets via the Utica Build-Out Projects, which include new construction and utilization of existing pipelines.  These projects connect many of the Midwestern refineries to the Utica Shale production and ultimately provide the ability to reach the Chicago, Illinois area refineries and pipelines that supply diluent to Western Canada.  A detailed summary of the product types, origination locations and destination locations can be obtained in the "Notice of Open Season".  The estimated in-service date for all of the Utica Build-Out Projects is anticipated to be mid-2017.

Open Season Process
Documents and further details related to the binding open season will be made available upon completion of a Confidentiality Agreement, available at:
http://www.marathonpipeline.com/cornerstone_open_season/           
OR    
http://www.mplx.com/cornerstone_open_season/

All interested shippers should submit an executed Confidentiality Agreement to:
John J. Staler
Senior Attorney
539 South Main Street, Room 887-M
Findlay, Ohio 45840
Telephone: 419-429-5831
FAX: 419-427-3695
Email: jjstaler@marathonpetroleum.com

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About Marathon Pipe Line LLC
MPL operates one of the largest petroleum pipeline systems in the United States, based on total volume delivered. MPL operates approximately 6,000 miles of pipeline in 14 states. These pipelines range from 4 inches to 40 inches in diameter. MPL transports crude oil, refined petroleum products and refinery feedstocks to and from terminals, refineries and other pipelines. MPL safely controls the movement and delivery of an average of 120 million gallons of crude oil and petroleum products daily through its pipelines. For further information on MPL, visit the company's website at http://www.marathonpipeline.com.

About MPLX LP
MPLX is a fee-based, growth-oriented master limited partnership formed in 2012 by Marathon Petroleum Corporation to own, operate, develop and acquire pipelines and other midstream assets related to the transportation and storage of crude oil, refined products and other hydrocarbon-based products. Headquartered in Findlay, Ohio, MPLX's assets consist of a 99.5 percent equity interest in a network of common carrier crude oil and products pipeline assets located in the Midwest and Gulf Coast regions of the United States and a 100 percent interest in a butane storage cavern located in W.Va. with approximately 1 million barrels of Natural Gas liquids storage capacity.

Contacts

Investor Relations:
Geri Ewing
Marathon Petroleum Corporation
419-421-2071
gcewing@marathonpetroleum.com

Teresa Homan
Marathon Petroleum Corporation
419-421-2965
thoman@marathonpetroleum.com

Media Relations:                            
Sid Barth
Marathon Petroleum Corporation
419-421-2850
swbarth@marathonpetroleum.com

Commercial Contact:
Jason Stechschulte
Marathon Pipe Line LLC
419-421-2317
stechschulte@marathonpetroleum.com

This press release contains forward-looking statements within the meaning of the federal securities laws. These forward-looking statements relate to, among other things, statements with respect to forecasts regarding capacity, rates, incremental investment and timing for becoming operational for the opportunities discussed above, as well as MPLX's future growth and results of operations. You can identify forward-looking statements by words such as "anticipate," "assess," "estimate," "prospective," "would," "will" or other similar expressions that convey the uncertainty of future events or outcomes. Such forward-looking statements are not guarantees of future performance and are subject to risks, uncertainties and other factors, some of which are beyond the control of the company and are difficult to predict. Factors that could impact the opportunities described above are: the timing and extent of changes in commodity prices and demand for crude oil, refined products, feedstocks or other hydrocarbon-based products; volatility in and/or degradation of market and industry conditions; completion of pipeline capacity by our competitors; the ability to obtain required regulatory approvals on a timely basis; the occurrence of an operational hazard or unforeseen interruption; and the factors set forth under the heading "Risk Factors" in MPLX's Annual Report on Form 10-K for the year ended Dec. 31, 2014, filed with the Securities and Exchange Commission (SEC). Copies of MPLX's Form 10-K are available on the SEC website, MPLX's website at http://ir.mplx.com or by contacting MPLX's Investor Relations office. In addition, unpredictable or unknown factors not discussed here or in MPLX's Form 10-K could also have material adverse effects on forward-looking statements.