Retaining Wall Stabilization
Challenge
Our team completed concrete lifting and repair on the driveway of Carolyn and Richard who had called us regarding routine servicing of the caulk we installed connecting their driveway with a retaining wall. It was cracking and they wanted us to inspect.
During the inspection, our specialist, Mike Lattero, not only noticed cracks in the caulk, but also some cracking on their patio stair steps, as well as in the bricks of the wall itself. This is typically indicative of structural damage. Their home was located on a hill and the driveway was located at the top of the hill. It was held level on the slope by the retaining wall made of block and covered by a brick veneer. The 32’x24’x8’ wall showed no settlement when a laser level was placed on it, however, it was bowing outward about 1” starting at the 19’ mark of the backside.
Carolyn and Richard were pleased with the remarkable experience we had provided from our concrete lifting service and they wanted us to provide a solution which would stabilize the wall and prevent further movement, while also potentially lifting the wall to its original position.
Solution
This was a tricky fix for us as the structure was positioned on a hill, meaning some of our more common solutions wouldn’t be possible since we didn’t have access to the inside of the structure like we would with a basement or crawl space. Despite the adversity, our specialist was dedicated to finding a solution.
Upon further evaluation, he recommended using Helical Soil Nails drilled into the soil underneath the driveway, which would then be connected to the wall to prevent further movement. The soil nails are attached to a threaded steel rod which is then fed through a wall plate and screwed onto the wall itself. The bolt on the outside of the wall plate can be tightened around the rod during dry seasons to potentially straighten the wall over time. The proposed plan for this project involved the use of 6 Helical soil nails, 3’ from each corner, and 5 ½’ from each other.
The first step was to cut holes in the wall to make room for the blades of the soil nails to get through. The crew experienced an unexpected issue when they noticed that the block wall was not fully attached to the brick veneer. This meant that attaching the wall plates to the brick veneer would not stabilize the wall as the block was likely the issue. This challenge was easily overcome by removing just enough brick that a wall plate could be attached to the block behind.
Once the holes were created in the wall, it was time to spin the soil nails. Each soil nail was made up of a helical blade on the front end and 2 leads with each section being about 5’ in length. A small cap on the nail end linked the nail to the threaded steel rod. The soil nails were installed using a Helical Drive Head attached to the end of a mini-excavator and spun just over 15 feet deep into the ground. Once the soil nails were installed, the threaded rod was then screwed into the cap on the end of the nails. The rods were fed through wall plates which were then attached to the exposed block wall underneath the brick veneer. The final step was to cut off the excess rod sticking out of the wall plate.
This project was completed in only one day and both Carolyn and Richard were very pleased with the results and the increased security we provided for their retaining wall.
Project Summary
Specialist
Mike Lattero
Team Leader
Michael Gunsolus
Materials Used
Helical Soil Nails (6), Leads (12), Wall Plates (6)
