Stopping Vibration from Walmart trucks

Add a Glass wall to the outside fence. Plastic? Plexiglass? Clearly the old fence stopedd the problem. SO I say go back to the fence as the cure. Notto tear down the new one. but perhaps you can add something to SOME of the areas like a plexiglass shield. (make it portable at first) so you can move them say ten feet) around. and find the spot which STOPS the noise in the house.I have to say in my apartment, placing insulation, just plastic bubble wrap like mylar coated? stopped the endless (depending on the direction of the wind) train nighttime noises in the bed room. I only covered part of the bedroom window inside the outer glass, and between some. SO half still allows light. It stopped 100% of the night time (distant, only if the wind was toward my place) train noise for me. So another way might be to dampen the GLASS with a transparent sheet of material stuck to the glass in some areas? Are your window glass double? double glaze? or single pane? MOST of the noise is coming in via the glass. IMO. And yes it was blocked by your old fence. You could even make a hinged or folding barrier.. Up at night, down in day in the yard next to the fence.
Finally try a roll of plastic film. To test the idea of the fence thing. Roll of plastic material stretched across along the fence. Covering the ’holes’ in the fence with an actual barrier. Thin/temporary yes, but to SEE if it works, perfect. If you want to really be cheap. cardboard.. and packing tape...

elizabeth +1, that could very well be where the noise is filtering through: your window, which acts like a drum skin, or a passive radiator, and passes the noise right into your home. That, or the fence, which could be argued, prevented the noise from reaching your windows. 

I'd google all the different ways to isolate all manner of noise abatement for windows, if after testing for it, like elizabeth suggests, proves to be  the culprit. Maybe heavy duty double or triple pane windows that face Walmart. 

All the best,
Nonoise

Truck out of there asap MOVE big time dude!!

Another possible method would take some time, and a lot of fiddling. Make three or so boards, with perhaps wooden stakes. Arrange them in the yard toward the Store area offending you. One closer, the the two back to the sides. In a V like arrangement. They would not need to be any taller than say half the fence?? WAS. but up in the air nearly as high. Just like baffles... Really IMO all you need is a slight attenuation and it would stop the strange artifact inside the home.Perhaps starting with them line of sight from windows to dock?
Another possible way Costing $$$, is a loudspeaker noise abatement system in your yard. The system picks up noise, and plays cancelling anti noise..

Plant some evergreen trees.