DIY Hill Mound

bob2oo7

Hi all
Currently in the process of digging up the garden (for beds, patio, laying new grass etc.)
I have a plan to re-use all the soil I dig up by making a hill mound out of it, with a slide coming down it for the kids etc.
I have one question, I would like to put a tunnel through it, something like this:

https://goo.gl/images/snwS7t 

I am struggling to find any supplier of these kind of plastic tunnels in Ireland... does anyone know where I could find it, or suggest anything else to use 
Obviously it would need to be safe to hold the weight of the dirt and people on top of it etc. 
Thanks in advance

looksee

What about these? http://condronconcrete.ie/concrete/pipes-accessories/concrete-pipes/

Plastic would be easier on knees but any of these mounds I have seen have used concrete as above. A couple of coats of concrete paint inside would help.

Lumen

You can get PVC lined concrete pipe, but probably difficult to work with.

How about HDPE pipe?

https://www.cotterillcivils.co.uk/land-drainage/large-diameter-pipe/

"Diameters from 750mm to 3500mm"

Lighter and could presumably be cut easily with angle grinder.

edit: or this in 600mm, has smooth wall internally

http://www.draindepot.co.uk/600mm-i-d-x-3m-unperforated-twinwall-pipe.html

bob2oo7

Thanks for the replies. Yeah I was trying to avoid concrete... it would be very hard to get it into the back garden as there is a bend between the house and shed to work around. Also worried about the suitability for kids running in and out of it
This one here does look promising though
http://www.draindepot.co.uk/600mm-i-d-x-3m-unperforated-twinwall-pipe.html
I will see what the story is with delivery costs etc.

looksee

You can of course tip the pipe on end to get it round corners!

bob2oo7

Lol, yeah of course, but concrete is heavy and there isn't room for machinery to get in and around I'm afraid