how to integrate a flood wall into a garden design

the_pen_turner

hi there

my neighbours house floods . thankfully it hasn't happened lately (a miracle given the floods everywhere) but it has come up level with the floor or just below it

anyway she is fed up of the stress and worry.
we want her to build a wall around the house to keep it out and pump any water inside out over the wall


my question is , she is into gardening. but the wall would have to go trough her lawn a bit.
I don't want the wall to look like a prison.

she could cover the wall in stone etc to look old (its an old cottage) but that would be a big cost .

I am hoping to design the layout of the wall to be more interesting and intentional from a landscaping point of view


any one with any ideas to liven up a mass concrete wall

thanks alan

Sonnenblumen

are you familiar with the structural requirements as well building regulations governing such developments? If not, may I suggest you do the right thing and refer your friend to a professional.

the_pen_turner

Sonnenblumen wrote: »

are you familiar with the structural requirements as well building regulations governing such developments? If not, may I suggest you do the right thing and refer your friend to a professional.

im not doing the building. my uncle who does ground works and build tanks retaining wall would be doing it.
all that would be on him.


my involvement is that I want it to look right and maybe come up with a layout of some way to design the aesthetics so that it fits in to a bigger garden design

my3cents

How high are you going OP, and what exactly is the flooding problem.

We just have some bumps in the garden to stop the flood that can come at us through the fields but if I had to do anything more major I would go for raised beds with terraces in front and a hedge on the outside.

I'd also add a lot of drains inside the area leading to a low area with a sump so the water you are going to pump away gets to the lowest point as quickly as possible.

But in some areas no matter how fast you pump water will just come up through the ground and thwart you anyway.

The real expert here is the practical person who has seen how the floods develop and knows the land.

the_pen_turner

my3cents wrote: »

How high are you going OP, and what exactly is the flooding problem.
going to build a 1200mm wall . flooding problem is a river nearby backs up and overflows out into the fields around her house. it rises up enough to put 12" of water in her house
We just have some bumps in the garden to stop the flood that can come at us through the fields
we were considering building a bank around her site but there is a ditch there so the bank would be inside that and would be a pain to keep the grass topped. also there would be a possibility of the bank breaching and letting in a wave of water really fast. that would be worse than just letting it slowly come in
but if I had to do anything more major I would go for raised beds with terraces in front and a hedge on the outside.
this is more what im looking for
I'd also add a lot of drains inside the area leading to a low area with a sump so the water you are going to pump away gets to the lowest point as quickly as possible.
the plan is to great a channel on the inside so that any water will enter the channel and flow around into a sump where it will be pumped out when the flood is there but leave through a pipe into a soak pit normally

But in some areas no matter how fast you pump water will just come up through the ground and thwart you anyway.


The real expert here is the practical person who has seen how the floods develop and knows the land.
I have lived there for 30 years and her 50 years,

I am more looking for ways to disguise or make a feature out of the wall

looksee

Would it be feasible to disguise the wall as a bank?

my3cents

If the wall is two walls with soil between you can plant whatever you like between the walls. Outer wall could be reinforced concrete and wall facing the house could be more ornamental. In some places it can be pure wall others narrow raised bed and in another perhaps wide enough to have steps or grass slope up to a grassed area. Inner wall could also have holes in in for planting into the wall.

I'd also corrugate the wall so from above it looked liked looking at corrugated iron roofing 6 - 12 ft sweeps. That would create nice sheltered planting areas. Perhaps outer wall straight with inner wall corrugated that would create a more interesting bed shape to plant up. If corrugated on the outside aswell then that would give good spots for planting tall shrubs or even trees to break up the walls outline.

There are loads of things you could do. You could even clad the concrete with timber so it looked like a fence. At the very least a trellis along parts of it will break it up a bit.

Last time I looked there were at least 600 ornamental varieties of ivy that would grow up or down the wall and plenty of shrubs that would benefit from the shelter.

I'd also think about using rough sawn pressure washed planks of wood (bring out the grain) for the shuttering so there was a very obvious texture to the concrete.

And from experience I'd go as deep as possible with the foundations where I am a full meter wouldn't be enough.

my3cents

looksee wrote: »

Would it be feasible to disguise the wall as a bank?

I have banks to help divert and hold back water and the problem is maintenance. I strim them 3-5 times a year and its a pain.

the_pen_turner

my3cents wrote: »

If the wall is two walls with soil between you can plant whatever you like between the walls. Outer wall could be reinforced concrete and wall facing the house could be more ornamental. In some places it can be pure wall others narrow raised bed and in another perhaps wide enough to have steps or grass slope up to a grassed area. Inner wall could also have holes in in for planting into the wall.

I'd also corrugate the wall so from above it looked liked looking at corrugated iron roofing 6 - 12 ft sweeps. That would create nice sheltered planting areas. Perhaps outer wall straight with inner wall corrugated that would create a more interesting bed shape to plant up. If corrugated on the outside aswell then that would give good spots for planting tall shrubs or even trees to break up the walls outline.

There are loads of things you could do. You could even clad the concrete with timber so it looked like a fence. At the very least a trellis along parts of it will break it up a bit.

Last time I looked there were at least 600 ornamental varieties of ivy that would grow up or down the wall and plenty of shrubs that would benefit from the shelter.

I'd also think about using rough sawn pressure washed planks of wood (bring out the grain) for the shuttering so there was a very obvious texture to the concrete.

And from experience I'd go as deep as possible with the foundations where I am a full meter wouldn't be enough. i meant a meter above ground
we are planning to use a drainage bucket to go down 4 feet into the ground and then put a widen foundation on too with the wall on top of that

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these are the ideas im looking for. thanks

my3cents

Our house is in the valley in the alluvial soil brought down by the river and while that water goes a quickly as it comes it also comes up through the ground so we'd need to go very deep to even start to slow it down.

btw you can also vary the height of the wall to give it a bit more shape and form. I'd also have a spare pump because ime they always fail when you need them most and have a few places where water could be let back out through the wall, Wavin pipe with end stops.

How will you handle the entrance or is that not in the flow of any potential flood?

Also water pressure can be huge as I'm sure you know so I'd be shaping the walls layout so it moved the water along rather than plain blocking it. Also the corrugated style of water might have a bit more strength?

the_pen_turner

my3cents wrote: »

Our house is in the valley in the alluvial soil brought down by the river and while that water goes a quickly as it comes it also comes up through the ground so we'd need to go very deep to even start to slow it down.i don't know very much about soil.
my usual gardening tools are strimmer, chainsaws, knapsack of roundup , or a mini digger:eek::eek::eek:.
I know that there is good soil for vegetables there and is about 1foot on one end and 2/5 foot on the other end of the field.
there is a few stone out crops in the fields next to it

btw you can also vary the height of the wall to give it a bit more shape and form. I was thinking about that but it adds a lot to the cost. I was going to cap the wall to take some of the look off of it changes in direction are a lot easier to do

I'd also have a spare pump because ime they always fail when you need them most we have an electric pump and her friend has a petrol one . hopefully we would cover it until she would hire one if needed
and have a few places where water could be let back out through the wall, Wavin pipe with end stops.
my plan is to have a channel on the inside to bring the water to a sump location. I will put 4" pipes into the wall so that any water that goes into the channel from rain etc on a normal day will go out the pipe.
then have a soak pit outside the wall

How will you handle the entrance or is that not in the flow of any potential flood?
im looking into a commercial solution but might end up setting 2 4" channel irons and dropping down 6x3"s into the it and putting a rubber gasket between

Also water pressure can be huge as I'm sure you know so I'd be shaping the walls layout so it moved the water along rather than plain blocking it. Also the corrugated style of water might have a bit more strength?
the water isn't really flowing or going anywhere. it just gets higher. the direction of the river is parallel to her house but the water goes around in a circle

thanks for taking the time to reply

Victor

A smaller(?)version of this? http://lloydkahn-ongoing.blogspot.ie/2011/05/giant-berm-protects-single-family-home.html Planning permission likely required. Realise that by excluding water from one area, you may be flooding another.

However, realise that if a property is surrounded by water that evacuation might be the best route: http://www.theatlantic.com/photo/2011/05/mississippi-floodwaters-roll-south/100069/

Note that it would still be useful to be able to approach the building with vehicles and that you need to deal with drains, septic tanks, wells, other underground services and water rising through the ground.

Of course, a better solution would be to build on land that is well above the flood plain or at least build the building above the flood plain.

the_pen_turner

Victor wrote: »

A smaller(?)version of this? http://lloydkahn-ongoing.blogspot.ie/2011/05/giant-berm-protects-single-family-home.html wow that's some work. I wouldn't want to be in there is it gave away
Planning permission likely required probably but looking into that. Realise that by excluding water from one area, you may be flooding another. there is a 20 acre field flooded, up 16 feet of water in one spot, I don't think 70 feet square of water would rise 20 acres my any more than 1mm if at all. but it is a legal issue if it could be proven to flood someone else's house

Note that it would still be useful to be able to approach the building with vehicles and that you need to deal with drains, septic tanks, wells, other underground services and water rising through the ground.
I am planning to keep one wall away from everything my 8 feet so that any future work can be done . any mini digger or such can come in front gate and around the house. the septic tank is outside the proposed wall. it too far out to be included. all that can be done would be to plug the pipe if the water started to rise. the grey water is separate but inside the wall so we would block the line out to the percolation and could pump the grey water into a tanker or ibc etc and let it into someone else's system (probably my uncles grey catch tank for the milking machine)

Of course, a better solution would be to build on land that is well above the flood plain or at least build the building above the flood plain.
unfortunately that boat has sailed pardon the pun. this house is an old cottage that was built 100 years ago by the coucil:o:eek:

.

my3cents

Another issue can be the septic tank flooding. Don't forget to take into account the percolation area. No point putting a wall across the middle of the percolation pipes giving the flood water an access route.

At the entrance you might like to raise the drive like a speed ramp which will allow a bit of time for further defenses to be put in place. Beware that any barrier needs to be held down so the water doesn't float it off. I think the entrance may be a problem area. Any cheaper solution that works may take too much time and skill to erect to be any use.

my3cents

With regard to the water coming in under the wall through the soil you could try a little test. While the ground is still saturated dig a hole deep enough so you have at least a foot of water in the bottom. Then pump it out and see how long it takes to refill. A bit of back of envelop calculation will give you an idea of how much water could come up through the ground inside any wall you build. I know you will be taking water from the surrounding surface area to start with but you will still get some idea of how quickly the water can move through the soil. If you make the hole deeper you can pump out from various depths and watch the hole refill to see what layers are the most porous.

Don't forget about old land drains. Often old cottages would have a box drain (box made of flattish stones or just rubble) running around the drip line of the thatch in lieu of a gutter. The rub is they often still work so if you cut them with your wall you suddenly have water that won't drain that used to drain away and if you don't then you have another route for the flood to come in.

the_pen_turner

my3cents wrote: »

Another issue can be the septic tank flooding. Don't forget to take into account the percolation area. No point putting a wall across the middle of the percolation pipes giving the flood water an access route . the septic tank and its percolation are outside the wall location.
the grey percolation is out side but the tank in in the way. I plan to move the grey tank inside and join back up to the outside percolation.
when the flood is threatening. we can put in a few pressure testing bungs to seal off the pipe to the septic tank and also the pipe to the grey percolation.


At the entrance you might like to raise the drive like a speed ramp which will allow a bit of time for further defenses to be put in place. a ramp would be a pain at the entrance and could make driving out dangerous. poor visibility so you need to go forward and back gently . If the water was higher than the entrance it would be in the house Beware that any barrier needs to be held down so the water doesn't float it off good point. I think the entrance may be a problem area. Any cheaper solution that works may take too much time and skill to erect to be any use.

.

the_pen_turner

my3cents wrote: »

With regard to the water coming in under the wall through the soil you could try a little test. While the ground is still saturated dig a hole deep enough so you have at least a foot of water in the bottom. Then pump it out and see how long it takes to refill. A bit of back of envelop calculation will give you an idea of how much water could come up through the ground inside any wall you build. I know you will be taking water from the surrounding surface area to start with but you will still get some idea of how quickly the water can move through the soil. If you make the hole deeper you can pump out from various depths and watch the hole refill to see what layers are the most porous.

Don't forget about old land drains. Often old cottages would have a box drain (box made of flattish stones or just rubble) running around the drip line of the thatch in lieu of a gutter. The rub is they often still work so if you cut them with your wall you suddenly have water that won't drain that used to drain away and if you don't then you have another route for the flood to come in.

I will see if I can dig a hole and see.
I don't think it will give a full picture but will give an idea.

saabsaab

I would go for a moate and raised dyke arrangement around the house. i.e.drain say 3 ft deep and raised 3 foot on the house side. Back this up with a concrete sump on the house side at the lowest point to put your pump. At the driveway gate you would need as indicated earlier a raised bump and a floodgate that screws into place like you see in Salthill, Galway. Usually made of Aluminium.