THE PROJECT: Replace failed retaining wall... the mission, to save the large pond above before spring rains wash it all down the hill!
When we received the call to look at this wall project, it was mid February, the 18th to be precise. Upon arrival, I noticed that not only was the site a difficult and challenging site for several reasons, I will mention in a moment; but also that time was of the essence if we were going to save the pond above this wall!
Yes, as we will see on the next page, there is a pond above this failed wall that was home to a school of Small Mouth Bass that were not wanting to meet an untimely death!
As I studied the site I could see that this wall had failed for many reasons: located on a very steep grade coupled with an inadequate footer, heavy topside pressure, & no support structure behind the wall. If we get a heavy rain the pond could be washed down hill and the fish lost...
As you can see the grade is very steep! Access at the wall is difficult as well... no part of this project was going to be easy. (EXCEPT working with the Smith's, they were wonderful!) I considered the many challenges with completion of this project and looked at the weather forecast ahead. It looked like rain was coming but then we might have a short window to work in after the rain passed.
I recommended tarping the most vulnerable areas of the hill side so the rain wouldnt wash more dirt away; having done this we went to the drawing and design phase of this project in order to present to the Smiths the plan to replace this wall and an estimate of the costs to do this project.
I have placed on the photo to the right, several green dots to highlight wall blocks that have rolled down the hill after toppling. The grade was so great that we would have to go beyond any standard rock based footer for the new wall. The soil type was clay and much had been disturbed during the house construction. We would need to take that all into consideration.
The pond pictured here was still covered to protect the fish from the colder temps. The dimensions of this pond were approx. 22W 'X40'L with the deepest areas around 4 1/2 feet.
The proposed concrete
4000 psi concrete mix / fiber
1/2" Rebar re inforced
A well drained compacted base made up of 1" Ballast washed rock; complete with 4" drain tile under the footer as well as behind the wall
This cutaway drawing shows the wall set on top of the footer
A detailed set of drawings along with the estimate was presented to the Smiths. The plan was approved and work would start the 1st week of March.
The project is underway! The old wall is removed in sections... and the frost/anchor footer installed.
Work began and was completed with a 3 man crew, an excavator and track loader. We also brought in black dirt with our dump trucks to fill in behind the wall and in front as well. This upgrade in soil from the clay that was on sight, provided very nice planting beds.
We stayed on the job till it was finished.
The extra excavated dirt is used on the front side to make possible for machinery access; as well as when we are finished provides a nice walkway and lawn tractor access.