Lifting concrete path to find drainage pipe 5 inches in?

[Stuff82]

I've just started lifting a concrete path in my back garden with the intention of then replacing it with soil & grass.

The concrete path is approximately 8 inches deep which I thought was a bit overkill, but just after starting it I found that there is a drainage pipe no more than 5 inches into the concrete that seems to head off to main road about 200 metres away.

Is it wise to remove the concrete & replace with soil as I'm sure that pipes should be buried more than 12 to 18 inches in the ground?

Or am I going to have to leave the concrete in place & try to lay a thin layer of soil & lay grass on top?

 

[ban-all-sheds]

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[Stuff82]

Untitled

• Stuff82
• 30 Apr 2014
• 1

Untitled

• Stuff82
• 30 Apr 2014
• 1

 

[hoodie786]

looks like some sort of ducting

 

[JohnD]

is it black plastic? What diameter?

Put your hand or a hammer in the photo to give scale.