Storm channel drain

[gc100]

We have a slope running down from a field to the side of our build. During heavy rain there can be a lot of water running down here which would try and enter the house those the glazed sliding windows. 

So I'm wanting to put a good storm drain across this section of the house and run into a large drainage pipe to one side which will just lead into an existing drainage ditch. However I'm struggling to size the channel drain (something like this https://www.drainage-channel.co.uk/category-6084/DCPC908.html )

 

I need something that can handled flash flood type downpours but have no idea how I could calculate what size, aside from just going with my guts! 

 

Any ideas?

 

[jamieled]

At this scale, your gut might be the best bet. There are a variety of methods for runoff calculation, but at the small scale blockage risk usually results in up sizing culverts, drains etc by quite a bit. The specific local conditions in your field will have a big impact on runoff coefficients.

 

Is there anything you can do to alter the direction of runoff if your chosen drain size is exceeded on occasion?

[gc100]

2 minutes ago, jamieled said:

Is there anything you can do to alter the direction of runoff if your chosen drain size is exceeded on occasion?

 

No not really. I had this in a house I lived in before (in France), we used to have to open the front door and it ran through the hallway entrance and out through some patio doors!!!! I don;t want to have this happening again hence why I'm thinking about oversizing this by quite a lot. 

My only other option would be to landscape the land so that the water split as it came down the slope and ran to either side of the house - but I'm not too keen on this as it would effect what would be essentially our garden.

[PeterW]

Put a diagonal field drain in. 
 

Dig a trench about 12” wide and 24” deep, you can put a pipe in the bottom if you want but don’t make it parallel to the slope, make it run down the hill slightly. 
 

Then back fill it with 20mm coarse gravel to the top. Don’t worry if it starts to grow with grass, just try to keep some of it clear. It will stop a lot of water. 

[gc100]

4 minutes ago, PeterW said:

Put a diagonal field drain in. 
 

Dig a trench about 12” wide and 24” deep, you can put a pipe in the bottom if you want but don’t make it parallel to the slope, make it run down the hill slightly. 
 

Then back fill it with 20mm coarse gravel to the top. Don’t worry if it starts to grow with grass, just try to keep some of it clear. It will stop a lot of water. 

 

While I'm sure that would work my only issue with that is the same as above - we'd basically have this running diagonally across what will be our garden lawn so not ideal

Edited October 15, 2019 by gc100

[PeterW]

So use it as a path across the lawn..?? 
 

You need to slow it or stop it before it gets the house or build a big French drain around the property. 

[Oz07]

My friend in oz had a long drive running to his shed which used to flash flood. Put in 2  runs of channel drain running diagonally sorted it out. Maybe 2 lots of standard size is cheaper than 1 special big size?

[Cpd]

 Can you provide a landscape photo of the area from the doors looking up the field? It’s always best to try and stop water at its start point rather than where the problems are showing themselves, I had this exact problem as I have a small glen up behind the house and in heavy rain all the water would come down directly to the back of the house and run through the back door and out the front  !!!!! This is when I first got this Run down place. I went up the hill beyond my property and with the consent of the landowner dug a deflection ditch as @PeterW states and this moved the water to yet another drain that fed it into my pond. I then did some minor adjustments to path levels to shed any surface water away from the house to a gutter down pipe drain. Everything has been working well for 7 years. If it’s a rural location I much prefer an open drain / ditch as it’s  much easier to see if they are working correctly and it’s a quick job to maintain them with a spade if vegetation becomes a problem. There are other options but some more detail of the situation will help. 

[gc100]

Thanks all, I think I will put an open trench between the field and what will be are garden and then put a large channel drain across the side of the house. I think that would do.