SECOND SUPPLEMENTAL INDENTURE VALERO ENERGY PARTNERS LP, as Issuer VALERO REFINING-TEXAS, L.P., as Co-Issuer THE PREMCOR REFINING GROUP INC., as Co- Issuer VALERO REFINING – MERAUX LLC, as Co-Issuer VALERO REFINING NEW ORLEANS, L.L.C., as Co-Issuer...