Ignore the immediately previous post. LS screwed up somehow. This is what I was trying to post-
Big, big difference in water volume requirements between a waterfall and a bubbler. You should not need a pump vault, but you will need a basin of sufficient size and sturdiness of construction to allow for ease of access to the pump and to support the weight of a 5' urn filled with water without settling, cracking or buckling. Many sizes and configurations are available from several manufacturers. I would recommend a 40" wide basin. A 300-500 gph mag drive should cover your needs in the pump category.
"Everybody is ignorant, only on different subjects." - Will Rogers