Before bolting it down, place the street bench exactly where you plan to anchor it. Don’t assume the concrete pad is flat—most aren’t. Crouch down and look under each leg. If you can slide a coin or a thin shim under one foot while the others are touching, that’s your first clue.
Next, put a spirit level on the seat in two directions: front to back and left to right. Side-to-side should be nearly dead level. A slight front-to-back slope is okay for drainage, but don’t let it lean sideways.
Then do a rock test. Push down hard on each corner, one at a time. Listen for a knock and watch for movement. A balanced bench stays silent and still.
After that, set your anchor bolts loosely—just enough to hold position. If the bench still rocks, add stainless or composite shims under the low legs. Don’t try to force it flat by tightening the bolts; that can twist the frame, strip anchors, or crack the concrete.
Finally, have someone sit on each end and the middle while you watch. Recheck with the level under weight. If it’s still solid, tighten the bolts gradually in a pattern and check once more.