The very bottom section of a shaft or sump where groundwater and runoff collect before being pumped out of the mine. Keeping the water level at the fork is essential to prevent flooding the lower working levels. When a pump has drawn the water down as far as it can reach, the mine is said to be in fork.
Heard on the job
The new submersible pump finally got the shaft in fork, so we can send the timbermen down to inspect the damage.