An injection well system is disclosed. The injection well system includes an injection wellhead having a lower master ball valve disposed at a first lower portion of the injection wellhead, an injection wellbore connected to the first lower portion of the injection wellhead, and a nonmetallic check valve disposed below the Earth's surface and at a pre-determined location of the injection wellbore, where the nonmetallic check valve, when closed, isolates the injection wellhead from a second lower portion of the injection wellbore.