How to level backyard for playground?

[mfaizi]

 

Hi guys again

Its been a tedious and expensive journey for our “dream house. From dodgy carpenters losing 40k on “materials order” and not showing up and disappearing- to finding hidden expensive flaws in our property.
We have finally reached the fun time for the garden and our kids to reap in the benefits of our anguish.

I purchased a lifespan swing set but wanted a level ground rather than a 20 deg slope, after finally getting rid of the AWTS and trying to level with topsoil i figured it would be an impossible exercise without some sort of retaining solution

using the colorbond fence as a guide for the degree of slope, what suggestions would say is suitable for making our kids dream a reality?

options are:

1) level as is and put on top

2) sleepers around and level and recycled rubber or turf

If there are more suitable options or more practical solutions please advise.

[Jewelleryrescue]

Hi @mfaizi 

You could  use a  landscaping technique of cut and fill. This will save you money having to buy  dirt to fill a one ended retaining wall.

Say we have a 20 meter  playground you wanted for the top of the hill to the lower part.

Now draw a line at the middle of the 20 meter mark this is your new play ground level.

Now take all the dirt from the top section of the  area and level it flat to match the level at the middle.

Now put all that cutting soil into the bottom half  so it also should now be level with the middle assuming the hill is a  uniform slope.

You will need to  put a mini retaining wall at the top cut as there will be a drop off and the bottom will need a  raise mini wall made out of  many materials.  The top area may need a slight slope still built in to allow rain water out with out plumbing in drains.

Brick , sleepers landscape blocks Treated pine  Sleepers.

The longer the cut the higher the retaining walls will need to be.

[mfaizi]

hi @Jewelleryrescue,

thank you for the detailed response.

i did look into cut and fill but have no idea in measuring gradients. 
is there a resource or technique that you can direct me towards to allow me to calculate the gradient?

Visually, i can see the left and back side are the higher ends of the slope and they both slope down to the right and front, in terms of cutting i would need to remove soil from the back and left and fill the front and right. The confusion is about how much soil needs to be removed and the placement of the retaining wall.

any information would be greatly appreciated 

Thank you in advance

[Jewelleryrescue]

Hi @mfaizi 

To measure a  gradient  is to measure the Length divided by the rise or fall.

One way to do this  for an estimate is to use a  one meter spirit level The Length.  touch one end to the high side and then hold it level and measure the gap at the other end to the  ground. Say the  gap is 200mm  The fall  .  So the the  gradient is (Length) 1000mm divided by 200mm (fall) which means the gradient is 5 in that mock  example.

I think the best way forward is to look at the flat play area you want to create and peg out the corners.

Now you can look at where you need to cut and fill like you already have  RE  "Visually, i can see the left and back side are the higher ends of the slope and they both slope down to the right and front, in terms of cutting i would need to remove soil from the back and left and fill the front and right."

The  goal is a flat area so stand in the middle of that play area and look up the hill now  all that  dirt needs to come down to the low area  below the middle of thee  hill/

Where the retain walls go is at the start and finish of the flat play area  As your hill is on a angle the retaing wall will form in the top corner and the bottom  corner.  AS a  guide.  All the soil needs to be transfered from the high side to the low side You will know how much soil  is  moved once all ground is  flat  ie level  with the middle point.

I would  highly  recommend you hire a  BOBCAT driver for half a day they know all about leveling and will go allthe hard soil moving work.

To  the forum members Any one know if there  are rules about cutting and filling re council etc?  Maybe a DP?

[JacobZ]

Hi @mfaizi,

Cutting and filling, as @Jewelleryrescue has mentioned, will give you the most level surface across the widest area, but it is a lot of work. If you'd like to go down this route, hiring a bobcat, or having an earthworks company do it for you will make it much easier. There are sometimes rules around cutting and filling so it is worth checking with your local council what your legal requirements are before starting.

You can measure heights in order to calculate the gradient in a few ways, with the easiest being a Lasertec HV2G Rotary Laser. It's unlikely you'd want to invest in one for a single job, so I have another method that's a bit more involved, but still a fairly simple way to do it. 

Put a stake in the ground at both the lowest point of the yard and the highest point of the yard. On the stake at the high point of the yard, measure up 100mm from the ground and put a screw in it. You can then run a string line from this screw to the lowest point in the yard. You can then put a Line Level on the string line, pull it tight, lift it until it shows level, and mark this point on the stake. You can then measure down from this point to the ground. Subtract 100mm from this measurement and it will tell you the difference in height between these points.

Calculating cut-and-fill projects is not exactly easy and is something usually done by civil engineers using complex maths. Unfortunately, I wouldn't be able to assist with this as it is well beyond what I am capable of.

Adding retaining walls so you can level a single area for your kids play set is likely going to be easier. 

Allow me to tag @Nailbag, @Noyade and @Dave-1 for their thoughts on your project.

Let me know if you have any other questions.

Jacob

[Nailbag]

Hi @mfaizi 

I see you have already had some terrific detailed advice from both @JacobZ and @JacobZSo, I only have a few supportive additions. 

I also highly recommend checking with council re the regrading. The main concerns they will have is if there are any easements to be clear of, which will be in your contract if sale. The other is any possible impact of water runoff to neighbouring properties. 

Definitely consider hiring a bobcat to excavate. They are typically around the $400/half day and can be cheaper for cash. Most drivers are very experienced in knowing exactly what’s needed to get on with the job very quickly and have the flat area pretty level just by eye to you in a position to check more accurately levels. 

You can hire dumpy laser levels to accurately and quickly check levels for around $70- half day. The hire place will show you how to use it so take a helper with you. 

Take into account the comment @Jewelleryrescue made re the effect of cut vs the height of the retaining wall. You really want to keep the height as minimal as possible as this can be an expensive build. You will also need to get that wall underway as soon as possible. We can advise you once the dimensions are known. 

Nailbag

[Dave-1]

AFternoon @mfaizi

Strangely I was just going through this type of scenerio the other day about landscaping

Nice large yard to play with and some falls to make it interesting.

I am presuming that concrete round thing is sewage or stormwater that cant be shifted/removed. I have one on my block as well btw.

I also would suggest what @JacobZ has with creating a flat area to install the swing in. Less work shifting tonnes of soil around. Also changing the way water will run over your block is something that just came to mind.

Here is a project I did on my front yard, check out step 4 half way down the page Stormwater update April 2024 You can see how I stepped through working out what I wanted in the yard, what was fixed and immovable (that concrete thing) trees and natural pooling areas of water is stuff I would think for you.

So a top down sketch of your yard as is, include fences, fixed things.

Next page, same view with the fixed things but add where you where you want the swing set and space around it to be level.

Next page yeah I know its a pain redrawing it but it really helps you in seeing the yard and seeing what you can do. This page sketch where the water runs right now, you could also include services such as power down your yard, water pipes for a tap (always handy having a tap out the back)

Last page, think BBQ area, trampoline, swingset, pergolla, shed, pond, garden beds, raised or not.

Here are the sketches I stepped through. I was looking for one that had all the heights I had estimated of the ground level with a laser level It still worked really well this way. So I took the top down sketch, and also a side profile one (just on the side so I could see stuff that id drawn) then worked down from the upper height of the yard. For me it was the steps, then first shrub was 30cm below the steps and about 3m away, I gradually worked my way around the slope I show so the slope had a gradual fall to it.

Same problem you have, you want a flat area, so retaining wall (yeah they are cheap, solid and very easy to build with no footings plus they can be shifted later

Different location for the retaining wall, next to the path. This is to shgow the steps I went through to sort out how to go forward.

A flatter area with the gabion wall high side. You could use the same idea to creat your area for the swing set and space around it. Id give lots of space around it

Side profile/front profile view type deal to see how it would look.

Water and where it would flow, store/pool was these sketches. The funky three pronged thing is a lamp post that is fixed.

I choose berms to slow my water flow around the yard and let it soak into the ground without trearing it to bits by straight run off.

Really fleshing out where I was going with the yard. With your yard, you have some high points, some low and you know where the water runs when it rains, incorporate these into an interesting yard.

So you can see how it actually ended up...

Gaurentee that you will be amazed if you do the sketches even to get an idea of what you want then plant it out and in a few years you are back here explaining to someone else what they can do The projects are all under my name in my bookmarks if you troll through them. I cant wait to see whichever way you go. There is no right answer! I almost removed my berms as they werent doing much after a year, had planned on the next weekend to get rid of them. Then it POURED and they worked perfectly Love to see some sketches!

Dave 

[mfaizi]

Great to see such a community. Truly appreciate all the advice. 
There was an opportunity to use bobcat through the yard as the “concrete thing” which was a decommissioned aerated water treatment system (awts) was collapsed and backfilled with the excavator. Problem is, my whole yard is very high and low and it would have been a very costly exercise to level one area and re-turf. I opted to level with topsoil and reseed patches for the remainder of the grass as the future plan is to extend the pergola etc which will take the space in the yard.

I have marked up an area using treated timber which works out approximately 5.5mx3m and am aiming to level the areas where the timber sits using a spirit level and trying to level the space inside as best as i can and putting either wetpour recycled rubber or rubber tiles as a workaround due to the potential other projects. 
what do you guys think??

[Dave-1]

Evening @mfaizi 

Treated pine sounds good (install drainage behind it to keep it healthy longer) and I would be doing the same with the spirit level. I am not sure about the wetpour recyled rubber or rubber tiles as to mainly water pooling/draining away. Also dont know about what steps you need to prep the soil beforehand. Is there a reason for the preference over lawn? 

Tho first preference I can think of is no lawn mowing

Dave