My clients have an existing pool with concrete paving. The new design requires permeable pavers around the pool. There are level changes 5' away from pool coping on both sides, one uphill, and one downhill. On the downhill side there is an existing retaining wall 6' deep with rebar upto the top. Is it ok to demo the top 12" of the retaining wall and connect to a new thickened slab that restrains the new permeable paving? The contractor says retaining wall rebar connecting to the slab edging will provide enough edge restraint. Is this enough, and if not how can we ensure the edge restraint will be strong enough? This is in an earthquake prone zone, and in the '89 quake the retaining wall did suffer some cracks.