I saw an opportunity to increase the storage area under our sink. First I removed the half wall and then moved the pump back a few inches. Next I cut the 1/2 wall down about 4 inches and then added a piece of plywood on top. I added some extra cleats ledger boards on the back wall so the shelf has a good ledge to rest on. I also added a front piece of molding so items on the shelf won't side off while going down the road. I did not screw the shelf down so I can just lift it out for access to the pump when needed. here are a few pics. This also gave us more room for a more normal size trash can , the one is there now is just temporally .