Photo Album: Sinking Patio/Drive Area in Need of PolyLevel in Grover Beach, Ca. Sinking exterior concrete. PolyLevel polyurethane foam needed to raise to level. Are Needing PolyLevel Sinking Concrete Slab Measurement of Sinking How much the slab has sunk Related content Before & After Photo: Using PolyLevel® For Uneven Concrete In Oceanside, CA