Drainage Problems

[ChiangMai2]

Hello Forum

I have a few areas in the garden that recently have become very wet. Water in some places is a few inches deep, perhaps 16sq meters or more for both area's, 32sqm total.

Originally I assumed that the pool had a leak as the problem is close to the pool and sala. We turned the pool pump off for a few days and the water level stayed the same so I don't think it can be that. Its not rained for weeks and the sprinkler system isn't close to the problem area. Its all a bit of a mystery to be honest. I can only think that that area of the garden is close to the water table and the foundations to the sala and pool are causing problems with water draining away to a small stream about 15 metres away and a pond about 5 metres away. I don't think there is much I can do about that although it is strange how its bad this year and wasn't a problem the last 3 years! Anyway I need to get it sorted out.

If anyone can suggest anything I would really appreciate it. Friends have said dump sand on it, others mentioned PVC piping with holes and gravel and then turfing on top. Both idea's make some sense but I am hoping that someone here can either confirm or come up with a better solution.

Attached are a few photo's - not sure if they will help. Failing that does anyone know any proffessionals that could help in Chiang Mai?

Thanks for your help

CM2

[Rimmer]

I had the same problem over a M U C H larger area, I put in two french drains or as your friend calls it a plastic pipe with holes cut in (you can buy these ready made) We sank it in the ground about 12 inches, covered it with large stones then smaller ones giving way to granite then soil and grass over it, one drains into my stream the other into my pond. No more problem ever again, the water really gushes out though them into the pond and drains the land perfectly.

[trogers]

I had the same problem over a M U C H larger area, I put in two french drains or as your friend calls it a plastic pipe with holes cut in (you can buy these ready made) We sank it in the ground about 12 inches, covered it with large stones then smaller ones giving way to granite then soil and grass over it, one drains into my stream the other into my pond. No more problem ever again, the water really gushes out though them into the pond and drains the land perfectly.

If you include a layer of geotextile between stones and soil, it will be perfect.

http://www.engr.utk.edu/mse/pages/Textiles/Geotextiles.htm

[ChiangMai2]

Wow - thanks for the quick replies!

With the PVC pipe what sort of diameter should it be please ?

And providing I can't get the ready made piping and need to drill my own holes, what sort of size holes do i need to make and how many? As many as possible or will that lead to it getting blocked up?

Now that I know it called a french drain I can probably google it to get those answers but if you see this and can reply please do.

Also is geotextile readily available here in Thailand? Any leads on where to get it in Chiang Mai - or I can post a separate request in that forum. Thanks so much for your help. Regards CM2

[trogers]

You should be able to get geotextile at Home Mart Chiang Mai under the section of CPACdsign that does paving.

http://www.homemart.co.th/location_shop.as...mp;ParentID=311

http://www.cpacdsign.com/detail_product.php?productid=100

[ChiangMai2]

this might sound a bit silly but is the pipe supposed to be perforated all the way round? or is the bottom side of it supposed to be hole free? Just did some googling and can't seem to see any confirmation.. Also Thanks Trogers, I'll check out homepro.

[trogers]

this might sound a bit silly but is the pipe supposed to be perforated all the way round? or is the bottom side of it supposed to be hole free? Just did some googling and can't seem to see any confirmation.. Also Thanks Trogers, I'll check out homepro.

Home Mart is not HomePro...

I will use 2 to 3 inch dia. pvc pipes depending on expected volume of water. Holes should be drilled at the top half, allowing the bottom half to channel water. Size of holes should be half the size of the stone chips - 5-6mm dia. should do.

[Rimmer]

Yep as Mr T says holes in the top half only.

My workers in fact found it faster (they would wouldn't they?) to cut small triangle shaped holes with their angle cutters on the top half. We used a four inch pipe on the bad part and a 3 inch on the not so bad area.

Good tip about the GEOTEXTILES, I was always worried about small stones clogging up the holes and cutting down the drainage flow and that would as Mr. T says would make it perfect.

[ChiangMai2]

Yep as Mr T says holes in the top half only.

My workers in fact found it faster (they would wouldn't they?) to cut small triangle shaped holes with their angle cutters on the top half. We used a four inch pipe on the bad part and a 3 inch on the not so bad area.

Good tip about the GEOTEXTILES, I was always worried about small stones clogging up the holes and cutting down the drainage flow and that would as Mr. T says would make it perfect.

Thanks all - that's the weekend taken care of

[Tracer Round]

I'm not sure the previous replies are exactly what you need. They all address how to keep an area drained, but do not address the more important issue of how the water is getting there in the first place (given that it shouldn't be there at all). Putting hidden drains is nice for addressing the symptom, but does nothing about solving the problem of what is leaking or seeping.

It looks to me like something has ruptured. PVC piping should last forever, more or less, but they seem to break around my neighborhood with uncanny regularity.

Turning off the pump to the pool will not affect anything if it is the pool itself that is leaking.

I'd say it is either a leak from one of the vessels near there -- pool or whatnot -- or from an underground water pipe. Alternately, it could be that if your house is on a rise or hill, there may be a problem with a line or vessel uphill from you. If the ground above you becomes saturated, the water can seep for a very long time, even after it is repaired.

Funneling off the water is a good idea, but before you go buying a bunch of stuff, I'd want to know where the hel_l the water is coming from in the first place -- that's the real issue here.

[Artisi]

Correct, rectify the cause before you start trying to treat the result.

[cheshiremusicman]

Correct, rectify the cause before you start trying to treat the result.

We had the same problem sometime ago and it was at the end corner of our 14m x 5m pool, so we initially thought that the water was leaking out of the pool. This end of the pool was at the opposite end to all the feeds etc so we excluded the possibility of broken pipes. I dug out where the water was coming from and did a test on the water to see if it had any salt content with the strips that I use to monitor the salt level in the pool. I found that there was no salt detectable and therefore concluded that we did not have a leaking pool - thank goodness. I was pumping over 2500 litres of water a day out of the hole with a submersible pump and came to the conclusion that someone or something had disturbed an underground spring with building work.

We bought precut slatted pvc pipe some 5 inches in diameter and cross drained the whole area around the pool. The pvc was wrapped in the fine blue mesh of the kind that they use for horticultural purposes and tied with wire. We laid down a thin layer of fine gravel and then laid the pipes on top of this before filling in with gravel and finally topsoil and replaced the grass sods.

The garden around the pool looked a real mess for sometime, but the work was not in vain and the water drained away very

successfully. We also put in a few drain inspection units so that we could monitor the drainage.

The whole thing was well worthwhile and we still to this day don't know where the original spring came from.

When we have the torrential rains the garden now drains away beautifully so it is well worth the effort of maybe doing other areas of your land at the same time.

Interestingly enough the last time that I lifted one of the inspection covers there was no water to speak of flowing.

I've got a pile of photos of the work and will try to get them sorted out and put them on here. Good luck and if you need any other help just PM me.