The Brew Cabin

Posted: **Sun Feb 09, 2020 10:15 am**

Hi, helup!

I need to drain ground and surface water from a car parking area aprox. 350mÂ². Our property is built into a steep hillside, the ground is largely heavy clay, (we are in Northumberland), the ground is saturated 90% of the year.
The car park is behind and a few meters higher than our buildings, it is surfaced with compacted sub-base (money saving solution). Not only is the car park almost unusable due to the surface water, but the run-off causes damage and problems further downhill. This run-off problem precedes the car park being built but has been exacerbated by it I think.
I plan to put in a 150mm dia. twinwall perforated pipe along the 35m length of the surfaced area where it meets the hillside, in a trench 900-1200mm deep with all the trimmings. Possibly I might add a simple herringbone of pipes into the car park to help with the ground water.
Thanks to the excellent Pave Ex. (having only just lost my drainage cherry), I think I know pretty much what I need to do in the car park; it's where to channel the captured water that seems an interesting and maybe unique problem.
The only solution is to get the water to an inspection chamber which is aproximately 35m off to the side (and downhill thankfully). But, once we leave the surfaced area, the very rough ground slopes steeply away through numerous trees for about 30m then drops vertically for 7m of solid rock. The inspection chamber is below this 'cliff' next to the back of a building.
I was hoping that I could use a flexible unperforated pipe to link up to the rigid buried pipe. This flexi pipe would initially be buried but would come to the surface after a few metres because of the steep slope and then would drop over the cliff, go into the ground for 1-2m before it goes into the inspection chamber. It would be ugly, very ugly.
I can't find such a pipe, one that is UV resistant, can be connected to a 150mm twinwall, nothing seems designed for this solution. The closest I have found is ducting, which does not seem up to spec.-at all. (I think that I have found pipes that fit my idea on US internet stores, but not UK).
Any ideas please? You would be welcome to pay an onsite visit-

free of charge.
Thank you for reading and any interest,
W

Posted: **Sun Feb 09, 2020 1:06 pm**

Can you post up some photos?
Is the land all belonging to you?

Posted: **Mon Feb 10, 2020 3:55 pm**

dig dug dan wrote:Can you post up some photos?
Is the land all belonging to you?

Yes, the land belongs to us, (we are a charity). We provide accomodation for guests and have about twenty people in permanent residence.
I'm not sure that it will easy to illustrate but I'll have a go at photos as soon as the storm dies down, (lazy and wimpy).
Thanks for your interest.
W

Posted: **Mon Feb 10, 2020 8:00 pm**

Can you not just drain it to the hill and let gravity and nature take over from there?

Posted: **Tue Feb 11, 2020 10:19 am**

So, have I got this right? Your solution relies on a buried land drainage pipe to act as an interceptor for the car park, which then, because of the site, this pipe will have to emerge from the ground, traverse several metres, and then plunge down sub-surface again to join-up with an existing buried system: is that right?

In such situations, we would normally encase the above ground section in concrete or similar to give it adequate protection. I'm fairly sure PolyPipe have compatible UV-stable pipes that could possibly be used, but I really don't like pipework being visible - it just attracts the attention of eejits and vandals - so better to encase it.

Posted: **Tue Feb 11, 2020 11:36 am**

dig dug dan wrote:Can you not just drain it to the hill and let gravity and nature take over from there?

Maybe, if I continued with the perforated pipe for several metres beyond the car park. But that would affect whatever was lower down the hill, and there is stuff there such as a cemetery (animal), a path and a lawn. This is why we plumped for the inspection chamber idea. There is a natural stream that runs perpendicular to the pipe, which would be ideal to feed into but it is some way off and not really practical.

I am bleeding, sweating and swearing away trying to get photos uploaded, so far in vain....

Posted: **Tue Feb 11, 2020 11:53 am**

Tony McC wrote:So, have I got this right? Your solution relies on a buried land drainage pipe to act as an interceptor for the car park, which then, because of the site, this pipe will have to emerge from the ground, traverse several metres, and then plunge down sub-surface again to join-up with an existing buried system: is that right?

In such situations, we would normally encase the above ground section in concrete or similar to give it adequate protection. I'm fairly sure PolyPipe have compatible UV-stable pipes that could possibly be used, but I really don't like pipework being visible - it just attracts the attention of eejits and vandals - so better to encase it.

You got it right.

Noooooo!!!! I cain't! I cain't concrete it. The best I can do is sling some turf over it to hide it's ugliness.
It makes sense what you are suggesting, (I could concrete I guess that would be belt and braces)but it would be too much for this job I think, for various reasons. We do have eejits for sure, but it is an area that is almost never accessed by anyone, eejit or not, so I don't think I need to worry about someone puncturing it.
Vandals, are unlikely, we are in the middle of sparsely populated moorlands and farms, the locals are friendly.

I will check out Polypipe, ta.
I will continue to try and get photos.

Posted: **Tue Feb 11, 2020 3:41 pm**

Here's some piccies I bravely took this morning in 5mins. Even more braver was spending the rest of the day uploading. Imgur is the way to go! (Thanks to IanMelb in Noticeboard post).

This is from beneath, car park is upper right, you can see the crash barrier just above the gas tank. Where I am standing is the access to the car park, more cars are parked out of sight on the left of the steeply rising entrance. On the right, a trickle to a stream of water runs down by the wooden building in wet weather. Beneath me is a public road, very steep, one of the main entrances to our property. The road surface takes a beating from the run off - one of the reasons for this job. The hill is really a steep side of a valley, the watershed is a long way above all this and our property, takes twenty minutes to walk up to it.

This is from me standing at the top edge of the car parking area, the crash barrier is about 10m away, the drain would be running from right to left of photo just in front of where I am standing. You can see how the ground on the right is starting to fall away down to the lane where the first photo was taken from. You can't see it, but the compacted sub-base surface is churned with mud and has semi-permanent large puddles making it almost unusable at times.Please take a moment to appreciate that barrier; installed by a colleague of mine, dug by hand, concrete mixed by hand ':p', it is done proper good up to spec., several cubic metres of concrete I believe. A contractor levelled the area with a digger machine, the barrier went in after. The digger man will be out this summer to lower the ground level which is too high in places in relation to the barrier, and to smooth it out since it's settled a lot, add new sub-base. I hope to have drainage in before he does all that.

This is from me standing at the far left edge where the buried pipe will exit the car park and start to run downhill to the inspection chamber. The picture shows the back of the building which the inspection lies at the foot off. The run to that, flexible pipe or not, would go between the trees and mostly be on the surface or close to it. Look at those barrier footings! Should stop any guest reversing at 70mph.

Lastly from below, the inspection chamber is under the table with the flower pots. The pipe would be running down the bank roughly in the centre of this picture. The bottom of that bank is solid stone. You can hopefully just see the crash barrier next to the roof, (take a moment..... :O)
I hope the above is understandable .
Thank you for reading if you got this far.
P.S. If you are suitably impressed with the barrier, all the stone buildings you can see were built by amatuers like me. Though I can claim no credit, they were mostly finished before my time and way over my head in skill, I weep if the words planning permission are even whispered let alone laying stone etc.

The Brew Cabin

Draining a hillside - Land draining