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