How many people work at big pit?

Please provide more context. "Big Pit" could refer to many different things, such as:

* Big Pit National Coal Museum: This is a museum in Wales, but it is no longer a working coal mine.

* A specific mining operation: There are many coal mines and other industrial facilities that could be called "Big Pit."

Please clarify which "Big Pit" you are referring to so I can answer your question.