The infamous flooded patio problem...

[Mr Spock]

In recent times my patio next to the house, gets flooded. A lot of this is because the houses opposite are higher than mine so all their water comes down into my garden. It's usually bad when there's a high rain rate.

This was taken on 2nd November after 20mm of rain in 8 hours. Nowhere for the water to go; even the garden next to it was waterlogged. Fortunately it wasn't high enough to get into the shed where the 12" is kept. 

As a temporary solution, a couple of days ago I dug a 'sump' in the bit to the left. But, surprise, patio was clear after 23mm in six hours! I reckon it could handle three times as much.

This pic is a bit later after the rain had stopped. It was a little bit fuller at about 18mm of rain. 
One thing to note is where the arrow is pointing. This was a little fast flowing river! It shows why it gets flooded so quickly.

Good news is the water drained away from the sump quite quickly. There's still plenty of space for more digging though.

[happy-kat]

that was a nice quick remedy

illustrates the negative impact of tarmacking over front gardens for parking

[GrumpiusMaximus]

4 hours ago, happy-kat said:

that was a nice quick remedy

illustrates the negative impact of tarmacking over front gardens for parking

Our lawn always gets absolutely waterlogged in winter -mostly due to the clay but there is very little 'green' space in our development.  All the houses are directly onto paving, very little gravel, etc.  I'm tempted to dig a similar sump or French drain (without a pipe, just a gravel trap really) at the bottom of our garden.  Unfortunately, directly behind our garden is a small car park and I think there's concrete a foot down.

Councils really need to start thinking about water run-off better when approving housing.  It's maddening that it's still an issue and that there isn't a strategy for effectively dealing with it...

Your sump looks highly effective!

[Mr H in Yorkshire]

13 hours ago, Mr Spock said:

One thing to note is where the arrow is pointing. This was a little fast flowing river! It shows why it gets flooded so quickly.

Was that river coming in, or going out of the patio area? If out, do you need to be concerned where it's going (before you disappear into the sink hole). Here's a cheery thought suggested to me by a police detective, if you dug up all the patios how many bodies would you find?

[Swoop1]

Anecdotal data suggests that 'planting' a human appearing bone somewehere within the curtelage of your excavation might result in the police doing the digging for you....

[Hawksmoor]

My house was built on what was once a large pond for a large country house long demolished. There was no provision for surface water drainage when it was built. When I constructed a patio I dug out the puddled clay and constructed a huge soakaway under it.  I also planted bamboo in the borders. In 10 years it hasn’t flooded but I am currently overrun by giant pandas😂

[Rodd]

I had similar issues-a deluge almost washed away my observatory.  I keep my power converters in a cooler beneath the tripod.  Like a fool I did not think to place the drain plug on the downslope side, and I left it open!  Naturally, the cooler filled with water and sediment and ruined my power converters.  The observatory roll-off tracks were buried in mud.  No fun imaging in Southern CT.

[Mr H in Yorkshire]

As we are talking hydrogeology anecdotes, where I lived in London was downhill from Crystal Palace and our back garden coincided with what had been the river Efra. Most of the year that end of the garden resembled pictures of the Somme. For the benefit of the local frog population, which was abundant, I decided to dig a pond. A mere spade-depth down was un-oxidised clay (blue not brown) and the water table was so high that water actually squirted out of worm holes as I dug. The pond was very successful, come mating time the happy couples were cheek by jowl and we couldn't sleep for the croaking. Word got around and people nearby actually brought frogs to us that they had found in their own gardens, as if they were needed! In a pond about 8' by 8' there must have been 300 mating pairs and the pond was converted to spawn city. I like frogs.

[Mr H in Yorkshire]

7 hours ago, Swoop1 said:

Anecdotal data suggests that 'planting' a human appearing bone somewehere within the curtelage of your excavation might result in the police doing the digging for you....

Trouble is they are not obliged to repair the damage, and if they use a digger...

[maw lod qan]

Sorry to see your flooding problems.

Perhaps you could take advantage of it. Open a seasonal water park. Swimming, tubing and maybe mud baths!

[Mr Spock]

Well, the advantage is... my scope is now out on a dry patio! That's what it's all about.

When we get to warmer weather I'm going to put in some proper drainage channels most likely using perforated land drain pipes. I need to lift the patio anyway as it's sunk a little in places and a couple are cracked.

[jjohnson3803]

I had a sunken patio at my former house, but it never flooded.  I figured they either put in a bunch of drain tiles when it was built or maybe the thing was poured over a meter or so of gravel.    

[Mr Spock]

It's back. 33mm of rain today, patio is flooded, sump is full and overwhelmed. It's not as deep as before but still disappointing 😡

[SteveWolves]

I fear you may need to substantiate you sump and put a submersible pump in to get water into house drains.

[Mr Spock]

I think this is the reality of our weather now. This never used to happen.

Between today and yesterday we have already had half the month's average rainfall...

And it's not done yet - it's still pouring down 

[Carbon Brush]

+1 for keeping a submersible pump to hand.
I think this is going to be the new normal. Wet warm(?) winters.
My garden is soggier than anytime since moving here in 2007.
The fields visible from upstairs have more standing water than I have seen before - despite serious dredging in a nearby dike a few years back.
In neaby villages, surface drains are overwhelmed, resulting rivers running down roads.
I bought some new wellies for this winter and spashed out (pun intended) on good quality expensive footwear. A wise investment I think.

[Mr H in Yorkshire]

I blame it all on the Noah's ark re-enactment society. I think their HQ is just down the road.

Edited January 3 by Mr H in Yorkshire

[Mr Spock]

It's all drained now.

[cajen2]

3 hours ago, Mr H in Yorkshire said:

I blame it all on the Noah's ark re-enactment society. I think their HQ is just down the road.

Now, next on the list is to find two of every species of beetle.....🤣

[Mr H in Yorkshire]

17 hours ago, Carbon Brush said:

I think this is going to be the new normal. Wet warm(?) winters.

My highly competent meteorologist neighbour just released his December report - warmest and wettest on his 40 years of records. The bad news, at least in my 35 years of living here in Yorkshire, is that Jan and Feb are generally the most dismal months so although the days will be longer, I'm not celebrating the clear skies. I am really disappointed because I really love the winter constellations and I've scarcely seen them.

[Mr H in Yorkshire]

2 hours ago, Mr Spock said:

It's all drained now.

Seriously, have you considered making a proper pond in that area next to your patio, and making a decent drain for the outflow? If you are going to have to lift the patio for repair you might find where the water is currently draining off, and if it's not likely to create more problems, tap into it.

[Mr Spock]

The water has no where to drain to. Next door, which is lower, has a proper drain fitted. My flooding seems to have occurred only since they built a new wooden 'wall' and fitted decking. I suspect they have blocked off the water draining from the top of my garden hence why it is all coming down to the patio.

I have a plan for that... wait until the summer then did a trench up to the fence so when it rain the water goes where it used to 

[Louis D]

On 27/12/2023 at 17:40, GrumpiusMaximus said:

Councils really need to start thinking about water run-off better when approving housing.

Our part of Texas is quite particular about limiting runoff from impervious cover.  Developers have to build large catch basins with elevated outlets to retain most of the runoff and allow it to soak into the ground rather than run off into a stream, creek, or river.  This also limits the spread of pollutants from oil spills on pavement.

Here's one near my house with a little bit of water still in it just behind the spillway to the far right:

That whole open area can fill with water after a rainstorm like a temporary pond.  If it rains more than it can hold, the excess goes over the spillway.

[Louis D]

13 minutes ago, Mr Spock said:

The water has no where to drain to. Next door, which is lower, has a proper drain fitted. My flooding seems to have occurred only since they built a new wooden 'wall' and fitted decking. I suspect they have blocked off the water draining from the top of my garden hence why it is all coming down to the patio.

I have a plan for that... wait until the summer then did a trench up to the fence so when it rain the water goes where it used to 

Sounds like my neighbor who put in 2 foot high metal edging along the fence on their side.  This effectively created a dam and violated Texas law about blocking the natural flow of water and causing it to flood neighboring properties.  Rather than take them to court, I waited until they moved out and listed the home for sale.  When no one was around, I went over to their yard and ripped out all the metal edging to allow water to flow naturally again.  That was 20 years ago, and no new owners have ever tried blocking the flow again.

[F15Rules]

1 hour ago, Louis D said:

Our part of Texas is quite particular about limiting runoff from impervious cover.  Developers have to build large catch basins with elevated outlets to retain most of the runoff and allow it to soak into the ground rather than run off into a stream, creek, or river.  This also limits the spread of pollutants from oil spills on pavement.

Here's one near my house with a little bit of water still in it just behind the spillway to the far right:

That whole open area can fill with water after a rainstorm like a temporary pond.  If it rains more than it can hold, the excess goes over the spillway.

Nice photo..

..but what's that clear bluish coloured area running along the top of the photo from middle to the right?? I know it sounds ludicrous, but it almost looks like, er, cloudless sky??🤦‍♂️🫣😲

Dave