Retain or not retain that is the question

Hi all I am currently working on cleaning out a corner of my garden and really wanted any advice on if retention is even needed?
I have provided a picture (still work in progress) but at the highest point in the corner it’s approximately 4 meters high and slopes down on either side to ground level.

I have found many ways to do the retention it e.g.
1. Wood Sleepers
2. Landscaping blocks
3. Std brick/block wall
4. gabion baskets
5. Crib walls
6. Erosion control mat/mesh

However all options would turn out very costly just for me to plonk a shed in place surrounded by a bit of deck.

So any advice regarding if I would actually need any retention or suggestions on better ways to do it would be much appreciated?

Many thanks in advance for any advice provided!

TheJoeAverage
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You will absolutely need to retain it. That sort of height is an accident waiting to happen.

If access is very good, gabions might be the cheapest.

That's a hell of a hole

And you need a structural engineer for 4m.

Thanks for the replies, was looking at the 1m x 1m x 0.5 gabions, crazy how well they stack together securely.

Was hoping I might be able to save some money by filling middle with old bricks I might be able to get me hands on?

Either way its going to be a challenge all via wheel barrow down side alley unfortunately.

freddymercurystwin said:

And you need a structural engineer for 4m.

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Yeah, whatever you use, you are going to need it designed by an engineer. At 4m, you will have to think seriously about the thickness at the base if using a gravity structure such as gabions. Reinforced concrete will be much thinner.

You've every item on your list except poured concrete into form work.
Which is the best method.

Except the final bill might amount to £15 or £20k.

If access is bad how did you get so much stuff out?

You seriously need to consider other options, such as coming in through a neighbours perhaps? A wall like that is going to cost a lot but if the only access is a wheel barrow sized gate you will never find anyone daft enough to take it on.

Pumped concrete might be a possibility.

Are you guessing its 4m? It doesn't look that high in the photo, more like 2.5m?

Hi All

Thanks for the further comments, slight change I revisited the measurements, as first was taken with the large pile in place which I have moved back to base and have attached a new pic showing its actually 3.1m. There is some points its 3.5m one being where I done the first measurement but is just top soil & I was planning on levelling/clearing that bit anyway so can stick to 3.1m.

So if now 3m is this a game changer meaning I could actually go for something like a sleeper wall? as the thought of hand placing and barrowing the rocks for Gabions is scary long drawn out thought as where sleepers would be manageable by myself.

At this point I feel like there was light at the end of the tunnel and really hopped everyone would say I didn’t need much if any retention as chalk is good for drainage anyway as know all mine has gone to farmers fields for that purpose and had personally seen many big chalk verges/walls in/around Kent myself, none look retained to me other than the odd one mostly along rail lines which appear to use a metal mesh/net type finish with big bolts plunged in? So was thinking sleepers with lining and backfill to please the eye but now maybe not..

Back to access, both sides of my house are via gate access only and so far I have done the whole think myself up to this point. The usual drill has been use 5 days annual leave and work a full 7 days with hire of micro digger with the tracks that can go in to get it round tight access to the back. Then fill two wheel barrows at a time jump off and do the two tips into two 8y skips on driveway 1 to fill and 1 for overflow while waiting on skip exchanges and can do approx. 1x 8y skip a day if material is dug out and ready.

Up to now I have filled 18x 8y skips and would say there is just about 2-3 skips remain to finish off the area so have the April BH booked off ready to do this.

Maybe I am bit mad but have kind of secretly enjoyed it & actually wish I done this type of thing as a job to be honest as currently a desk jockey which is driving me mad. But flip side I bet I saved a fair bit of money.

I hadn’t thought of poured concrete form work & was not something I had heard off but the price sounds expensive. I think I may have been misled with google images and sleepers as solution up to this point as had seen many examples of big retention walls (Look big) using sleeper’s ether lying flat, or slid into concreted steel girders and some that stand upright?

But have now kind of hit a wall on this one and need to find best solution that also ticks the boxes around acceptable solution.

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TheAverageJoe said:

So if now 3m is this a game changer meaning I could actually go for something like a sleeper wall?

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No. There is no way you could ever retain 3m of soil using sleepers. The ground might look stable, but if it ever started to move the sleeper wall would be over before you could say "maybe reinforced concrete would have been a better idea"!

Reinforced concrete is going to be in the region of 350mm thick with a pretty long base.

If using gabions you will probably be looking at 2m thick at the base stepping in by 500mm for each rise of 1m, ending up at 1m wide at the top.

No idea what the cost would be for that but sleepers or unreinforced masonry are out of the question at that sort of height.

I'd use 1X1m gabion baskets stacked two high, and batter back the top 1m.
You can fill them with old bricks/broken concrete etc, and just face the front with stone. That retain it, no problem, and would be the cheapest solution.

themiddleagedun said:

I'd use 1X1m gabion baskets stacked two high, and batter back the top 1m.
You can fill them with old bricks/broken concrete etc, and just face the front with stone. That retain it, no problem, and would be the cheapest solution.

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Maybe, but if designed properly by an engineer you might still need the wall to be more than 1m wide at the base, as battering it back at the top (depending on the angle) makes almost no difference to the design forces at the base.
Angling the baskets back by a few degrees would help a bit and would help to make the wall a bit less imposing.

Still needs an SE design, despite what some may think .....

We do a lot of retainers without se's involvement.
Like this big 4.8m high beast a few years ago...
http://s26.postimg.org/7bbtyco89/Big_Retainer.png

Which was about 70m long in total.
Note how the foundation is deep within the unexcavated abutment to prevent sideways movement.
About 28 cube in that section which we can fill in about 2 hours. Next day it moves along and filled again.

A water drilling rig was just to the right which flooded us that particular day.

Norcon said:

We do a lot of retainers without se's involvement.

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Really? Who designs the base or the stem? Who checks it against overturning. How do you know what reinforcement is required or whether or not the ground can cope with the bearing pressure?

RonnyRaygun said:

Norcon said:

We do a lot of retainers without se's involvement.

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Really? Who designs the base or the stem? Who checks it against overturning. How do you know what reinforcement is required or whether or not the ground can cope with the bearing pressure?

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The backfill checks it against overturning.
Yeah we did have a few fail early in our careers. Before we knew what re bar was.