- "Pa" is used as 'it' when one refers to a spot as "it". For example: Panakalika means 'It (this place) can be sat on'.
- -chimba means to dig.
'-ika/-eka' at end of a verb shows the state of an object. That state could mean "Something(s) is/are already done. = [Subj + Me tense + ika/eka verb ending] Or Something(s) can be done, is/are do-able, is/are possible.... = [Subj + na tense + ika/eka verb ending]
Therefore, panachimba means, 'It (this spot) can be dug.
I have reported the inappropriate answer provide.
A hoe ((ma)jembe) is a digging tool used in farming. https://5.imimg.com/data5/PR/XX/MY-21853420/agriculture-hand-hoe-500x500.jpg In this case they manage to dig a hole/canal/something without one. I guess it has the pa- prefix because the hole/canal/something is a place rather than an object.