I'm going to start by stating the assumptions upon which my answer is based.
- I assume the area is unclassified; - that there is a circuit entering the back of the box; - that corrosion is a problem; and, - that the area where the wire is run- right along the curb- can be considered to be 'without traffic,' due to the heigth of the curb.
So, here's a solution: 1- Replace "Bell" box with 4x4x4 PVC box (you can drill opening anywhere in back); 2- From bottom of box, stub out PVC 90, continue PVC run slightly below grade; 3- At end of PVC, use a female adapter and a compression-type UF cable grip to attach UF.
As I see it, the "smurf" is being used for additional mechanical protection, and possibly to reduce a trip hazard. The only problem....if there is one...is that it appears the Smurf is connected properly to the box- which makes me wonder if there is anything mechanically connecting the UF. The wiring connections need some sort of strain relief.
I also suspect that the install was done with the box horizontal to prevent it from profecting above the curb; it is possible that a round box would also create such a trip hazard.
I'm tired of getting down on the ground for things like this. Maybe we could plant a cedar 4X4 and mount the bell box high enough so I could pull up a chair and be comfortable. I'm sure I'd be using something more "Rigid" than smurf tube.