Retaining walls:
Retaining walls performance is commonly poor in Arizona causing many adverse effects. In addition to the rotation of the wall itself which can possibly fail with no intervention, the housing, or other infrastructure located above the wall can fail. Many retaining walls are built in rows of 2 or 3 with the upper walls being built on the fill of the lower ones.
Grouts can be used to reduce the effective pressure of soil and water on the wall to mitigate future movement. This is usually most effective with thinner grouts or polyurethane grouts.
Helical piers are commonly used as tie backs to stop future rotation or even pull the wall back into position. (See tieback dwg).
Micro piles have advantages over helical piers as a tieback particularly in gravely soils with cobbles and rocks in the soil. This is common for Arizona soils and can many times lock up the helical piers before they can reach the depth needed to reach the passive zone that is needed to resist horizontal slide movements. Micro piles can drill through rocky soils to the depth that is required to provide horizontal slip resistance with out having to predrill for a substantial cost savings.