A sidewalk here fails at its joints before it fails anywhere else, and it fails by rocking. A panel 4 feet wide and 4 inches thick has no weight to hold itself still, so once the base under it is wet and soft every footstep tips it a fraction, and each tip pumps a little water and fine sand out through the joint. The panel settles at one end, its neighbor stays put, and the step between them is the trip edge the City marks in paint. Nothing lifted it. The ground let go underneath.
Goldenwest Huntington Beach Concrete has replaced sidewalk panels across Huntington Beach since 2017, and Scott Ferreira walks every frontage himself before a saw is started. Most of the walks here were poured in one go with the tracts between 1960 and 1975, many of them tight against the curb with no planting strip, so a street reaches the end of its walk all at once, and the panels that go first are the ones over the lowest, wettest ground.
A panel is replaced from score mark to score mark, on clean crushed rock that drains, poured at 4 inches, or 6 where a driveway crosses it, to the width and scoring of the walk either side. The walk is right-of-way, so the work goes in on an encroachment permit from Public Works and the inspector sees the forms. It is done under a CSLB C-8 license with liability insurance on every job, and carries a written workmanship guarantee against defects in how it was built.