Preparation for Artificial Grass

[benthom55]

Hi,

Over the years my garden has flooded after short showers, upon digging out the old lawn I have found the area has a thick layer of clay under the surface therefore I have decided to dig 5 - 7 inches down with a large hole in the middle to fill this with hardcore prior to laying my new artificial grass to act as a bit of soak away and hopefully stop water resting on the new grass.

Can anyone advise what would be best to use for the hardcore which would assist the drainage issues I'm having?... also a good place to buy from?

http://www.sandandgraveldirect.co.uk/index.php/hardcore/type-1-fully-certified.html - I have seen this Type 1 Full Certified Hardcore, However I did read somewhere that Limestone content wasn't good for this sort of area? This might be wrong.

Can someone point me in the right direction please?

Thank you,

Ben

 

[freddiemercurystwin]

Soakaways don't work in clay. How deep is the clay?

 

[benthom55]

Hi Freddy,

In the middle I have dug down about 2 1/2 to 3 ft and have hit some rubble, so I'm hoping that I have got all the way through it and the water will soak away more easily now.
Just querying the hardcore that should be used really.

Ben

 

[r896neo]

the bigger the stone the bigger the voids and therefore the more effective it is.

The ultimate is soakaway crates but large 40mm plus gravel or soakaway crates need to be wrapped in a geotextile membrane.

You need a clean single sized aggregate with no fines. or brick rubble etc as long as its clean.

 

[maplegardenservices1]

Hi,

Over the years my garden has flooded after short showers, upon digging out the old lawn I have found the area has a thick layer of clay under the surface therefore I have decided to dig 5 - 7 inches down with a large hole in the middle to fill this with hardcore prior to laying my new artificial grass to act as a bit of soak away and hopefully stop water resting on the new grass.

Can anyone advise what would be best to use for the hardcore which would assist the drainage issues I'm having?... also a good place to buy from?

http://www.sandandgraveldirect.co.uk/index.php/hardcore/type-1-fully-certified.html - I have seen this Type 1 Full Certified Hardcore, However I did read somewhere that Limestone content wasn't good for this sort of area? This might be wrong.

Can someone point me in the right direction please?

Thank you,

Ben

You have lots of options for land drainage and some are quite cheap but even the best will not work unless you do it correctly.

You need to find the water table to make a effective soak away.

Firstly you need to know how big of a soak away you need.

The formula i use is:

Vol = A × 80 (storm rainfall rate) /3000).

Then you need a trial pit to find the water table.

Dig a hole 1.2m deep then a trial pit 300mm square and 250mm deep at the bottom.

Leave it for 24 hours making sure its covered so no idiot steps in it and if after 24 hours there is no water in it you will have a great soak away, if there is water in it then that water will have stabilized at water table level and you can use it to determine if a soak away is possible or practical in that area.

If your water table is exceptionally high all you will create is a hole full of water commonly known as a sump.

In that case find another spot to put the soak away that works and use cheap land drainage pipes that cost £2 per metre ish to keep your area dry and move the water to the soak away.

 

[benthom55]

Thank you for your help guys.

I dug the hole a few days ago and no signs of water, so hopefully this spot should be satisfactory

I've found some 40 - 75mm clean hardcore, with some 20mm and 10mm to top and level the area out.

Thank you.