Outdoor Drainage Project: Retaining Wall in Small Backyard

The Drainage Problem: New Retaining Wall to Level Out Backyard and Direct Water Away

There were 2 goals to this project. Replacing the old wood retaining walls was the first and most important piece to the project. The old wood retaining walls were too tall after the dirt behind them had eroded and sunk down. There were no drainage solutions behind the wood retaining walls so water would seep through them and collect down below. Lastly, the wood walls were just not that attractive to look at. The other goal of the project was to fix the area down below the wall. This area was graded incorrectly and was often soppy and full of water. 

Step #1:  Outdoor Drainage Consultation

The customer reached out to us at KG Landscape and scheduled an outdoor drainage consolation with Kent, our owner and lead designer. Kent met with the customer at her home to observe the backyard hillside drainage issue in person. While there, he collected the site information needed to provide a detailed plan/estimate for a long term solution to the drainage problem.   

Step #2: A Detailed Proposal

After careful consideration of the drainage problem and the options available to correct the issue, we put together a detailed plan to solve the customer’s backyard drainage problems in a cost effective and dependable way. There were also a number of landscape design options that we discussed before landing on a final design plan for a brand new stone retaining wall with an exposed French drain running along the bottom of it to collect water.

Landscape Service Description 

Retaining Wall:

Remove and dispose of the existing wooden retaining wall. Then install a new retaining wall using Belgard straight faced retaining wall block with matching capstone. The wall will turn back toward the SW corner of the house in the backyard and end even with the corner of the house. Remove the existing fencing and posts that are in the way of the new wall section in the SW corner and also cut into the hill about 2’ before building the wall.  Install ¾” drainage rock and filtration fabric behind the wall with a 4” corrugated pipe that connects into (2) wall grates allowing water to move easily through the wall and into the French drain below.


Drainage Work

Install an exposed French drain along the base of the wall, the French drain will be an exposed rock bed 18” wide with the actual French drain being 12” wide. The rock bed will be defined along the lawn side with new poly edging (it would look like a rock bed above ground between the new edging and the wall). The trench created for the French drain will be lined with filtration fabric. A 4” corrugated perforated pipe with a silt sock cover will run down the center with a downhill slope in the pipe running from the North to the South end. A solid 4” corrugated pipe trenched in below ground that will carry water collected from the French drain along the side yard 90’ where it will end on the hill in front with a pop-up emitter allowing water to leave the system.




Lawn Grading:

Using a dingo (mini-bobcat) and hand raking, the lower portion of the lawn North of the sidewalk to the new retaining wall (or fence line) will be graded to slope smoothly away from the house and back toward the new French drain that will run along the base of the wall.  Soil removed during the grading process will be used as backfill above and around the new wall sections. Once this roughly 15 x 28’ area has been regraded it will be sodded with up 450ft2 of new sod. 


Step #3: Installation of Drainage Solutions

Step #4: Project Completion

All of the work described in the proposal was completed and thoroughly tested by running water through all components of the system. Both we and the customer were 100% confident the drainage issues have been solved in a high quality and reliably way.  We’ve kept in touch with the customer and they’ve had no more puddling, much firmer grass in the backyard, and no more erosion issues since this work was completed in 2019.  

We’ve never seen an outdoor drainage issue we couldn’t fix.  Do you have an exterior drainage problem? Call us today to schedule an outdoor drainage consultation at 763-568-7251. You can also submit a quick quote to our website to get in contact with us!