How to reduce the height of a retaining wall?

Question

Hello,

I have recently moved into a new property. There is currently a retaining wall with concrete sleepers going across the backyard, which is 900mm in height and goes about 2.5m in from the fenceline, making a large portion of the backyard unusable. The reason it is there is because there is an easement on the property, which the retaining wall runs along (but not on the easement) and the house behind the property is higher as the house runs on a slope. My initial hope was to move the retaining wall back as close to the fenceline as possible, but it seems like we will run in to trouble with the wall sitting on top of the easement at that point and council approvals. Another option discussed to dig out part of the soil and reduce the height of the retaining wall (to around 450mm) and put a non retaining fence close to the boundary line to divide the property. Is that possible and safe? If not, are there other suggestions on how to make the backyard into more of a usable space?

Nailbag · Answer

Hi @lado96

I  don’t think your questions can be answered in this forum. Though reducing the height of the top level sounds achievable, there are several other factors that I can think of and unknown.

My advice would be to consult with a domestic engineer qualified to advise based on all the elements.

Nailbag

Dave-1 · Answer

Good Evening @lado96

I understand the impact that raised section has on your backyard. Tho all thethings and steps that @MitchellMc has pointed out I agree with. Even if you put in a "non retaining wall" closer to the fence there is a fair chance it would weaken the fence posts support and you will end up havoing serious issues with your fence.

Council and maybe waterboard would be the first stop and then see what they say and go from there. I suspect it will be a no go tho.

As a note on easements. I have large round sewer concrete cap on the edge of my fenceline. I kept it clear for a few years and then got fed up and was trying to grow grass over it…. That is untill 11:30pm one night the front yard was lit up like a Christmas tree and the waterboard cleared the grass, lifted the lid and blasted the sewage jam underneath….. Oh yeah, there are always reasons for easements that we dont even suspect lol I was glad it happend as like you I was one step away from installing a solid fence that would cover part of it.

Will be crossing fingers for you :) Have you considered a ramp somewhere along it to allow an easier access? Better then stairs. Maybe from that left post along the retaining wall and up ending between the retaining wall and watertank?

Dave

JacobZ · Answer

Hi @lado96,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Before we consider what can be done, we need to understand the specific location and the reason for the easement. The type of easement and who it benefits will determine what, if anything, can be built over or near it. For example, if it is a drainage easement, sewer, or stormwater line, there may be strict restrictions on excavation, loading, and structures to ensure ongoing access and prevent damage.

Considering you are on the lower end of a slope, and you have a large drainage pit, then I'd say there's a good chance part of the reason for the height and location of the retaining wall is the drainage infrastructure that sits beneath the soil behind the retaining wall. Confirming with your local council what is there, and what is required under the terms of the easement is going to be the first step.

If you are able to reduce the height of the soil and thus the retaining wall, and still comply with the terms of the easement, then you would start by excavating and removing the soil and either regrade the land with a gradual slope or installing another retaining wall elsewhere. Due to the limited width of the area, I don't think a slope would be the answer, so you'd have to look at installing another retaining wall, to create a terrace, closer to the fenceline.

With this, you would then need to look at what your local councils' requirements are in terms of setback as permanent structures often can't be built within 1 metre of your property line.

So, I'd suggest you start by reaching out to your local council to see what the terms of the easement are and if there is any room for alteration. If there is, you'd then need to look at the rules around setback. If there is room for movement, then you would need to retain the soil elsewhere in accordance with the easement and your local councils setback rules.

Allow me to tag @Nailbag and @Dave-1 to see if they have any advice or guidance they can offer.

Jacob