I am looking at your original document that I googled for (your context is a bit sparse).

The context is that a compost bin needs to meet a couple or requirements, and this one is in the category 'structural requirements' for removing compost out of the bin.
"The composter must have a top opening large enough and at the right height so that compost mixing can be effected easily. The accepted maximum height is 1,30 meter. The minimum size of the opening matches a circle of diameter 50,0 cm inscribed in geometric figure chosen for the cover lid.
-Extraction of compost must be easy, and either be done:
- Through an extraction trap easily maneuverable and with wide enough opening.
- Out of a pan or a face, easily removable and sufficiently large to work at ease.
- By the uplift of the composter walls."

Pan or face in this context to me means een bak of een opening (removable pan of facing)