Rainwater drainage from patio

marylander · March 2011

Brand new to this forum, I am glad I found it! After looking through the solar pumping threads, I did not find anything addressing my question so I thought I should post it here.

Here is the scenario: I have a stone patio behind my house in Baltimore, MD which originally drained naturally. However, over the last 40 years, tree roots have grown under it preventing rainwater drainage. I suppose I could kill the tree roots and lower the patio but it would be a lot of work

and also I like my trees

. Therefore, I am considering putting a drain at the lowest point and pumping the water away(may even use it to water the trees). I would like to use solar for sustainability and also because I want to avoid the complexities of outside 120V AC power.

Roughly, I am thinking about putting up a solar panel (attached to a nearby tree, in fact the one that is responsible for the roots under the patio) that feeds a 12V battery (usually there is not a lot of sun when it rains...), presumably through a controller, that then powers a smallish 12V pump which is controlled by an automatic switch.

So, my question is, can someone give me hints on which components I should look for?

What panel (how many watts, recommend brands et)? For panel size, it may be important that we are under big trees so no direct sun during the summer.

I suppose choice of the panel will dictate choice of the controller.

What battery? I am pretty sure I want a flooded cell. Would an 8D be overkill? Perhaps two golf cart batteries? Or just some good size 12V marine battery?

What pump? I am a sailor so the first thing that comes to mind is a bilge pump. I thought of one of the small submersible centrifugal pumps (Rule is one brand) but then I thought that the hole I would have to make in the patio could be shallower if I used a pump somewhere else with a strainer (this would be a pretty big deal since the patio is a solid slab of concrete, so putting a deep hole in it can be done but not so easily). Is that a good idea? Suggestions for a pump? Also, I am concerned about winter. Are there pumps that survive freezing? Of course I could winterize the system in the fall (together with my boat) but then it would not work for 4 months.

What other components? For instance, is there a 'best way' to attach a solar panel to a tree? Maybe 10' high or so.

This is not a 'mission-critical' application, in the sense that something really bad happens if it occasionally fails but of course the hope is that it usually works.

Other information: The patio is about 30'x10' wide. The water would be rain water, so not silty or anything but there would be certainly debris from leaves etc. The water would have to be lifted about 2' and can then run of by gravity. So, it is not a whole lot of water and not a lot of head either.

Thanks for all input!

Cariboocoot · March 2011

Re: Rainwater drainage from patio

Welcome to the forum.

Let me be the first to say "If you've got grid, use it". Frankly, solar power is expensive.
Best case scenario would be to redesign the drainage so that no pump is needed. However, this might involve digging everything up and doing it all over with a resultant loss of trees.

In terms of figuring out what you should get you first have to determine how much water you need to pump, how fast, and how far. Once you've sized the pump you'll know how much power you need and be able to determine how best to get it. Drainage is usually a matter of high volume and low pressure. But pumping water in any configuration tends to be a big power user.

You also have an unpredictable factor; you never know how much it's going to rain. Nothing worse than getting in to a long spell of precipitation and having your batteries go dead because when it rains solar panels don't work to recharge the batteries.

There's another problem with freezing; pumps don't like it. "Freeze-proof" pumps are expensive and not 100% guaranteed.

I'd suggest putting in a sump with AC pump on a GFCI line.

waynefromnscanada · March 2011

Re: Rainwater drainage from patio

I agree with cariboocoot, he nailed it, told it like it is.
However if you have lots of money and want something expensive to play/learn with, then go for it.

marylander · March 2011

Re: Rainwater drainage from patio

Thanks, Wayne and caribocoot, for your candid replies. I really appreciate not being pushed in the solar directions at all costs, quite the contrary!

However, I do believe that solar does make sense. I agree that 'grid' would be a good solution if it were easily accessible. However, although obviously my house has AC and it is only ~10' away from the point where the water collects, these ten feet is where the patio is. I spent an hour yesterday with a cold chisel chipping away at the concrete under it and there is embarrassingly little to show for my labor! Getting an AC line to the location of the pump will be a major endeavor and entail a lot of destruction of perfectly good concrete (several hundred pounds by my estimate). Although this is not a huge factor moneywise (an 80# bag of pre-mixed mortar is only $6.- or so), it would involve a lot of (my) labor. Also, I don't want to destroy something really well built if I can avoid it.

As for the problem of not knowing how much rain will fall, of course you are correct. However, as I said in my original posting, it is not that something horrible will happen if water accumulates. I would only be back to the status quo which means, at the worst, a little water seeping into the basement during a really heavy rainstorm.

But you are making a good point, I should probably get some more information before I jump in with both feet. As it happens, I have an old bilge pump from my boat and even a float switch. So, to test the idea, I only need a battery.

So, this is what I will do: I will chisel a 'mini-sump' into the concrete, just 1/2" or so deep, for the business end of my sump pump (since the centrifugal pumps always leave some water). Place the pump there and connect it to a battery (to be procured) via the floating switch. For the time being, I will charge the battery with a car charger (which, of course, will be only connected intermittently as needed) and see if the whole idea makes sense. If it does, I will get back to the solar part later.

(Stupidly, I discarded a marine battery from the boat last fall. Its capacity was not sufficient anymore for on-board demands but it would have been perfect for this purpose. This would have made this is zero-dollar upfront project. Oh well.)

Again, thanks again for your input. I will come back with a report on how this turns out and potentially ask for more input on the solar part, hopefully with some more information at hand.

mike95490 · March 2011

Re: Rainwater drainage from patio

The tree roots lifted the whole side of the patio , evenly, no cracks ?? Roots usually have a pattern radiating out, restructuring a whole area seems odd.

Any thought the house side, settled, and changed the drainage that way ?

Well, regardless, the patio needs draining.

BB. · March 2011

Re: Rainwater drainage from patio

You can also contact a plumber or contractor that specializes in running piping underground by horizontal drilling/pressing... However, it may not be worth the costs unless you have other needs (add new drain piping, running electricity/natural gas to a back year BBQ area, etc.).

-Bill

marylander · March 2011

Re: Rainwater drainage from patio

mike90045 wrote: »

The tree roots lifted the whole side of the patio , evenly, no cracks ?? Roots usually have a pattern radiating out, restructuring a whole area seems odd.

Any thought the house side, settled, and changed the drainage that way ?

Well, regardless, the patio needs draining.

Well, the tree roots lifted the side of the patio which used to be the lowest part, where the water was designed to flow off. So now there is a nice puddle at what used to be the high part which is now the low part.

And yes, there are some cracks. Easily patched with some mortar...

marylander · March 2011

Re: Rainwater drainage from patio

BB. wrote: »

You can also contact a plumber or contractor that specializes in running piping underground by horizontal drilling/pressing... However, it may not be worth the costs unless you have other needs (add new drain piping, running electricity/natural gas to a back year BBQ area, etc.).

-Bill

I actually thought of that but I would think the amount of $$$ we are talking about is not in a sane relation with the amount of water that needs to be moved. Surely much more than even a super-duper solar installation... And no, I have no need for anything else being piped there.

westbranch · March 2011

Re: Rainwater drainage from patio

Marylander, you said "I would only be back to the status quo which means, at the worst, a little water seeping into the basement during a really heavy rainstorm. "

If this is true that little water seeping into the basement is the indication that something is wrong with your drainage system around the perimeter of your foundation, if there is some tile there...

I would suspect the tree roots have plugged/blocked the drainage pattern ans something more drastic is needed , like Mr Rotorooter. As Mike said the patio should have roots running in all directions, and not be 'even'...

they also have fiber optic cameras that can be used to 'scope out ' a plugged drain before major digging has to happen.

here is a good link http://www.nrc-cnrc.gc.ca/eng/ibp/irc/ctus/ctus-n69.html

cheers

icarus · March 2011

Re: Rainwater drainage from patio

I can't find the link right now as my sat link is too slow, but there are small 12 vdc dewatering/well sampling pumps out there for not too much money that would run on a small panel.

Alternatively, consider a "Rule" brand 12 vdc submersible bilge pump. They are ~ $25, have a built in electronic "float switch" to allow them to run automatically. Buy a ~ 50 watt panel, a 12 volt deep cycle battery and a Rule, and for ~ $250 you can play and see what works.

Tony.

Sorry for the lack of links, but you can find Rule at West Marine, or Boaters World.

T

marylander · March 2011

Re: Rainwater drainage from patio

westbranch wrote: »

Marylander, you said "I would only be back to the status quo which means, at the worst, a little water seeping into the basement during a really heavy rainstorm. "

If this is true that little water seeping into the basement is the indication that something is wrong with your drainage system around the perimeter of your foundation, if there is some tile there...

I would suspect the tree roots have plugged/blocked the drainage pattern ans something more drastic is needed , like Mr Rotorooter. As Mike said the patio should have roots running in all directions, and not be 'even'...

they also have fiber optic cameras that can be used to 'scope out ' a plugged drain before major digging has to happen.

here is a good link http://www.nrc-cnrc.gc.ca/eng/ibp/irc/ctus/ctus-n69.html

cheers

You are right, ideally there should never be water ingress into the house, so something is not perfect. I don't know what kind of drainage they put in when they built the house in 1960 but I imagine that they did not anticipate a great need for it, given that there is the 10' wide patio that was designed to direct the water away from the house. So, I don't know if there are underground drainage pipes that might have been clogged by tree roots.

Even now, it is only perhaps once a year when a little bit of water gets in the basement (say a gallon total). I am not too concerned about that, it is more of a cosmetic problem: having the puddle there after each good rain gets the patio full of dirt and I am tired of powerwashing the stones twice a year.

marylander · March 2011

Re: Rainwater drainage from patio

icarus wrote: »

I can't find the link right now as my sat link is too slow, but there are small 12 vdc dewatering/well sampling pumps out there for not too much money that would run on a small panel.

Alternatively, consider a "Rule" brand 12 vdc submersible bilge pump. They are ~ $25, have a built in electronic "float switch" to allow them to run automatically. Buy a ~ 50 watt panel, a 12 volt deep cycle battery and a Rule, and for ~ $250 you can play and see what works.

Tony.

Sorry for the lack of links, but you can find Rule at West Marine, or Boaters World.

T

Yes, that is very much along the lines I was thinking. I have an old Rule pump plus a float switch lieing around so I will buy a battery and play with that.

[BTW, Boaters World went belly up a year or two ago. I believe they still have an internet presence but I suspect that is pretty much a drop-ship operation. As far as brick and mortar boat stores are concerned, West Marine is the only one left, other than mom and pop stores]

dwh · March 2011

Re: Rainwater drainage from patio

Getting electricity under a slab, sidewalk or driveway is usually not a big deal - I've done it many times.

The two methods I used were to A) attach a hose to a 10' stick of rigid electrical conduit (the threaded galvanized pipe) and use it as a water drill.

or

I had a doohickey that I inherited from an old journeyman. It was home-made attachment that screwed onto the end of a 3/4" rigid pipe and had a shaft which I could chuck up in my 1/2" Hole Hawg drill. On the other end it had a regular pipe cap http://www.grainger.com/Grainger/Cap-2WJ67 with a bit of metal welded on the end to grind out the dirt. The bit of metal was a little wider than the cap. Basically a 10 foot long 1" drill bit.

Of course, neither one will work in rocks, but they generally slide along the bottom of a slab just fine.

peterako · March 2011

Re: Rainwater drainage from patio

It is also possible to make a simple roofing above your patio. :roll:

And collected the water and drain.

And you make a nice area from it

Peter greece

marylander · June 2012

Re: Rainwater drainage from patio

marylander wrote: »

Yes, that is very much along the lines I was thinking. I have an old Rule pump plus a float switch lieing around so I will buy a battery and play with that.

[BTW, Boaters World went belly up a year or two ago. I believe they still have an internet presence but I suspect that is pretty much a drop-ship operation. As far as brick and mortar boat stores are concerned, West Marine is the only one left, other than mom and pop stores]

OK, this is just because I am in the area

and I promised to report back. Where is the project? To start with, I have not yet installed anything solar and the problems are actually different from what I expected. The idea with the bilge pump and automatic float switch, powered by a marine battery, works great in principle. If we have a real storm (like one of our famous thunderstorms), there is no way that the small pump can get rid of all the water. But that is fine, the water overflows naturally where it always went. The important thing is that AFTER the storm, the little pump gets rid of the puddle which would result in to a murky area if it were standing there for days.

I put one of the little Harborfreight solar trickle charger on the battery, just because I had it and hope that it keeps up with the natural leakage. Charging is with a car battery charger. The pump is surprisingly economical, I need to do it maybe once a month. Still, at some point I want a real solar charger.

The problem is actually that there is quite a bit of debris (leaves, pollen, just general schmutz) that requires frequent cleaning of both pump strainer and switch. It is done in 5 minutes but needs to be done. I will need to build a better strainer system. Of course, it all needs to be cosmetically acceptable too.

Again, this was just supposed to be an update since I promised it. If I have more news, I will report again!

Rainwater drainage from patio

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