'Down' in the Bible

This is what the Lord says,“Though they are at full strength and many in number,Even so, they will be cut off and pass away.Though I have afflicted you and caused you grief [O Jerusalem],I will afflict you no longer.

Draw water for a [long, continued] siege!Strengthen your fortresses!Go down to the clay pits, trample the mortar!Prepare the brick kiln [to burn bricks for the rampart]!