Retaining walls and water are almost always bitter enemies. If a retaining wall fails, there is a good chance that the reason for failure has something to do with water. That being said, routing water away from your retaining wall is a very important step in the design process.
A common question that we get is if the toe and heel drains are necessary on every design. The toe drain’s main purpose is to collect and expel incidental water that makes its way through the wall rock right behind the wall but shouldn’t be used as a main drainage system. The heel drain is used to route water that has migrated behind the wall away from the reinforced soil mass.
While we always recommend adding toe drains, heel drains are not always needed. For example, gravity walls don’t have a reinforced soil mass to route water away from, and a wall designed with no-fines-concrete doesn’t need a heel drain because the water will flow straight through the concrete mass.
The reason that Allan Block always recommends a drain is because there is always a chance that water will get behind the wall, and it’s very important for the water to have a safe exit path that avoids the wall. Here at Allan Block it’s our goal to see all retaining walls designed and built properly and now that you know the importance of toe and heel drains, you can help us reach that goal.