Landscape Newsletter Issue 22
Print Document
Print/Download

Backyard Transformation Washes Away Water Problems
The Cleghern family from Tennessee Ridge, Tennessee were homeowners with a backyard problem that needed a solution. While their yard already had a pool, there really was not enough space around it to relax and entertain. This was due in part, to the large sloping hill at the back of their property. This hillside was also creating a serious drainage issue as well. With no constructive place for the run-off water to go, the excess water from the hillside was finding its way into the pool and flooding the crawl space under their home. The Cleghern’s needed a solution and they needed it fast.

Curved retaining wall with pattern and stepping down a curve

Paver patio with pool surrounded by retaining wall and privacy concrete two sided fence

The homeowners sought out the assistance of AB certified contractor, Will Pinkerton of The Plant Ranch and sat down to draw up a design for their new backyard. Their first concern was to find a way to divert the flow of water from the hillside to keep their home and pool from flooding. The Cleghern’s also wanted to open up the space for more entertaining possibilities and add privacy to their yard with a fence.

The contractor suggested building an Allan Block retaining wall to manage the slope and increase the useable space in the yard around the pool. Drains would be installed to divert the water and since the homeowners really did not like the look of a wooden fence, the AB Courtyard Collection was recommended to create a concrete wall that would provide the perfect privacy solution.

Courtyard two sided wall system with gate provides privacy

Backyard with pool with patterned retaining wall

The AB Collection from Allan Block was chosen to tackle the hillside. The homeowners really enjoyed the look and texture of the Ashlar Blend pattern to match the feel of their overall design. The contractor was able to push back the hillside 15 ft (4.6 m), and finished the wall on each end with step downs to follow the grade of the slope, giving them a lot more entertaining space. Drains were installed within and behind the wall to divert the water flow.

The AB Courtyard wall was placed at the back of the house and wrapped around the yard to meet up with the retaining wall. Landscaping was added to the area to provide the perfect mixture of aesthetics and privacy while still keeping the yard feeling open and inviting. Once the project was completed, the Cleghern’s yard was transformed from a washed out and confined space with no privacy, into beautiful and functional outdoor living space that they can enjoy with family and friends.


Water Management - The War on Water

Do you have standing water or muddy places in your lawn or yard? A slope on your project that is directing rain water toward a home or building, or maybe a parking lot or driveway with standing water every time it rains? If any of these scenarios sound familiar, then you have a water management problem. Adding a retaining wall and proper drainage options to your project is your solution.

Water is an important resource, but in the wrong places can be a very destructive force. In fact, 90% of all wall failures are caused by improper water management. This is why it is important to consider where the water on your project goes both during and after your retaining wall is completed.

Fighting the War on Water
Before we can begin to wage a war against water on a project, we must first determine the type of water present. Only then can we develop the solutions available to fight the problem. There are two basic types of water found on any given landscape project.

Site plan of house showing water drainage

  • Surface Water
  • Groundwater
Surface Water

Surface water can be defined as a water source above the ground. These water sources will need to be identified and taken into account during the design of the wall. Slopes above the wall, driveways, parking lots, roof downspouts, irrigation systems and outdoor faucets are all examples of surface water.

Groundwater

Groundwater can be defined as water that occurs within the soil. Sources include surface water infiltration, water table fluctuation and water moving above the layers of permeable soils. Groundwater movement must be managed before encountering the wall structure, including the soils behind the wall. Typically this type of water is not an issue on most projects, however, if during the excavation process you find water in your trench, be sure to seek help from a local engineer to ensure that the groundwater has been accounted for in your design.


Now that we know what types of water there are we can determine how best to manage them. There are three main ways to address the water on a site:

Terraced retaining wall with stairs with a slope above

  • Site Grading
  • Wall Rock Zone
  • Chimney & Blanket Drains
Site Grading

The main objective in any wall project where water is an issue is to divert the water away from the reinforced soil mass. Surface run-off is typically handled by diverting the water using berms or swales above the wall or by grading the site so that the normal flow of water is away from the back of the wall.

Site berms with a retaining wall
Berms

Site Swales with a retaining wall
Swales

Wall Rock Zone

The wall rock zone is comprised of a clean well-graded gravel material that provides many positives to the design and function of your wall. Its primary function is to provide a quality material for compaction in and around the facing. Also, it aids in the connection with the geogrid and shear between block courses. One of its secondary functions would be to provide a route for any incidental water that may get into the wall.

The wall rock provides an area behind the block and in the cores where incidental water can easily drop though to the toe drain and keep hydrostatic pressure from building up behind the wall. Toe drains are an important part of managing this incidental water. All drains need to be either vented to daylight or attached to an underground drainage system.

Retaining wall section showing how incidential water filters through the system
Wall Rock Zone

Chimney & Blanket Drains

A chimney or blanket drain is another line of defense in our war with water. This drain consists of a blanket of clean stone beneath the wall and a column of clean stone behind the geogrid reinforced structure. This allows the water to migrate downward toward the base of the wall where it can enter the drain pipe and make its way away from the wall.

Now that we know what types of water there are and the different ways we can combat them, we can better prepare for the water that will inevitably be present on the project site. As with any project, make sure you consult with your local engineer to ensure the water is accounted for within the design. Water will be defeated and the project will be the victor!


Retaining wall cross section showing drain pipes

Chimney Drain


Ending Your Wall with Step Downs

When using a retaining wall to tame an unruly hillside or simply adding more usable space to your landscape, how you end your wall can be just as important as how you began. Building with step downs is a beautiful and functional way to complete your Allan Block retaining wall project.

Why use a Step Down?

In a large number of retaining wall projects, the site has been re-graded to allow water to flow away from the wall as well as other structures that may be present on the property. Typically the wall will follow this new grade change and slope. By stepping the top of the wall down you are able to follow the grade of the slope being retained as well as providing an aesthetically pleasing finish to your wall. Step downs can come in a variety of styles:

Typical Step Down

Simple and straightforward, this option steps down each course using a full size block and an AB Cap block to add the finishing touch.



Step Down with a Return

Turn it in - this option steps down each course by using a corner block at the end of each step down. This provides a finished look to the slope.



Graceful Step Down

Create a soft ending to your wall by implementing an inside curve as you step down. Whether using a typical step down or gradual step down method, this graceful option is sure to please.



Gradual Step Down

This option allows you to step down the wall with a subtle sweep. Use the AB Lite Stone or AB Barcelona block as a half high step as you move down the wall.

Retaining wall stepping down a slope

Retaining wall step down with a Return

Retaining wall curve stepping down a slope

Retaining wall using smaller blocks to end a wall with step downs

Step Down/Planter

This option allows you to step down over a longer area and can also be used as a planter. Simply turn the wall in 2 or 3 blocks after the AB Corner Block, or use a curve to soften the look.

Retaining wall stepping down to create a plantable area using corners Retaining wall with curved walls stepping down a slope

Illuminate Your Projects
Lighting brings new possibilities to any landscape. Add a dramatic look with ground mounted lighting or illuminate stairways and pathways with recessed lighting. Allan Block retaining walls with decorative lighting fixtures provide not only a distinctive design, but add safety and security to the landscape.

Allan Block's patented hollow core design makes it easy to add lighting into any wall. Simply run the wiring directly behind the AB blocks (follow local electrical codes) to the light locations. Use a masonry saw to cut out sections of the block to accommodate the lighting fixture and run the wiring through the blocks out to the light fixture.

Backyard patio with terraced walls, stairways, lighting

Graphic showing lighting through an AB Block

There are a wide variety of lighting types to illuminate your landscape. Choose the lighting option that fits the look and feel of your landscape.

Retaining wall lighting option on a block Retaining wall lighting option in a block Retaining wall lighting option in the landscape Retaining wall lighting option in the landscape accenting the wall
Cast a soft pool of light
with a wall mounted
light fixture.

Add soft general
lighting with a
recessed light fixture.

Illuminate
pathways and
garden accents
with a pathway light fixture.

Silhouette
accented
landscape
features with
a bullet light
fixture.


Need more options?  Check out some of these websites for more ideas.