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What Do I Need to Know About Retaining Wall Drainage?

Table of Contents

When designing and constructing retaining walls, integrating a robust drainage system is essential to ensure their long-term stability and effectiveness. Here’s a deeper look into the key aspects highlighted in the discussion about drainage systems for retaining walls:

Understanding Hydrostatic Pressure Behind Retaining Walls

The Impact of Hydrostatic Pressure

retaining wall drainage

Hydrostatic pressure refers to the pressure exerted by a fluid due to the force of gravity. In the context of retaining walls, this fluid is water that has saturated the soil behind the wall during rainfalls or snow melts. The accumulation of water increases the weight against the wall and pushes against it, which can cause bulging, cracking, or complete failure. Thus, implementing a method to alleviate this pressure is critical to the longevity of any retaining wall.

How Drainage Reduces Hydrostatic Pressure

Proper drainage systems are designed to prevent the build-up of hydrostatic pressure by allowing water to flow away from the wall. This is achieved through various means, such as perforated drain pipes, graded backfills, or drainage tiles, which collectively work to redirect water, thereby reducing the stress on the wall.

Drainage Systems for Different Types of Retaining Walls

Integral Drainage Solutions for Impermeable Walls

Walls constructed from materials that do not permit water to pass through, such as poured concrete, require comprehensive drainage systems. These walls are often equipped with a combination of drainage tiles and rock or gravel backfills to facilitate water collection and rerouting. Additionally, proper outlets must be installed to ensure that the collected water can be discharged away from the wall effectively.

Natural Drainage Features in Permeable Wall Designs

Contrastingly, walls that are inherently more permeable, such as those made from boulders or segmented blocks, often require less complex drainage systems. The natural gaps between the stones or blocks in these walls allow for some degree of water seepage, reducing the risk of hydrostatic pressure build-up. However, even these walls benefit from some level of engineered drainage to ensure long-term stability.

Best Practices in Retaining Wall Drainage Design

Site Assessment and Drainage Planning

Before constructing a retaining wall, it is essential to assess the site for water flow patterns and soil types. Understanding these factors helps in designing an effective drainage system tailored to the specific needs of the site and the type of wall being constructed.

Material Selection and Installation Techniques

Choosing the right materials for drainage—such as the grade of gravel, type of perforated pipe, and fabric filters—and installing them correctly are paramount. These materials play a vital role in capturing and redirecting water, preventing soil from clogging the system, and ensuring that the drainage continues to function effectively over time.

Regular Maintenance and Inspections

Post-installation, it is advisable to perform regular maintenance checks and cleanings of the drainage system. This ensures that it remains free from blockages and continues to operate as intended, especially after heavy rains or seasonal changes.


retaining wall drainage

Incorporating a robust drainage solution into the design of your retaining wall is essential to counteract the destructive potential of hydrostatic pressure. Whether your wall is designed to be impermeable or naturally permeable, understanding and implementing the correct drainage strategy will play a critical role in its durability and effectiveness. Regular maintenance and periodic inspections will further ensure that your retaining wall remains safe and functional for years to come, protecting your landscape investment. If you have any questions or need professional advice, please don’t hesitate to contact Natural Environments Corporation today for more information.




Our landscaping services in Minneapolis St. Paul – Twin Cities include landscape design, retaining walls, boulder retaining walls, stone walls, rip rap, shoreline erosion control, patios, driveways, helical piers and more.


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