Poll: Local Stormwater Management, What Do You Do With Your Rainwater Runoff?

[Morakot]

This is a poll about stormwater management for people who live in houses where there is a realistic possibility of local stormwater management. Please don't vote if you live in a condo or town house without any possibility of independent stormwater management.

There is also a broader discussion on impervious surfaces here which relates to this thread.

Edited May 12, 2013 by Morakot

[Crossy]

I voted 'other' our runoff from the house is piped directly to the khlong which in turn goes into the river.

Rain that falls on the garden is used by the plants.

[doglover]

Other.

Eavestrough piped to ceramic urns. When these are full the flow will be directed to the storm water pond. If the pond is full then runoff will be directed outside the fence into the rice paddy.

Edited May 19, 2013 by Rimmer
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[IMHO]

Only one of my houses needed it's own stormwater system (all others have city/project/condo stormwater drainage) so my soakaway vote reflects that.

[JAS21]

All the drainage from the houses in our village, the roads, the grass areas, run into culverts which are beneath the village roads. From there the water runs in a large underground area at the end of the village. It is pumped out from there into the local Klong.

Actually there is a pump bypass valve through which water can run into the Klong so long as the Klong level is not too high.

[bbradsby]

You need to add a button in the poll choices for "Khun Yai running from urn to urn with flexible hose connected to roof gutter outlet."

[Spoonman]

I stay indoors when the sky's open up so am not sure where my runoff goes to.

[kannot]

I dug a hole 1600m2 and 8 metres deep. problem solved

[kannot]

I stay indoors when the sky's open up so am not sure where my runoff goes to.

Down hill??

[luudee]

I have a question about storm water management.

Right now I have a soak away for my rain water. I have a well for my regular water. No city water/run-off.

I have a large garden, about a 1/2 rai green area. Does it make sense to collect rain water in my case ?

I'm thinking when it rains, I don't need the water, so I would have to put one or two really large tanks under

ground. I'm thinking 5-10K liters (total) ... I have no idea how long that would last. Bus cost wise, it's the

same as pumping the water from the well (ok, almost). So what would be the justification for this ?

Thanks,

luudee

[IMHO]

I have a question about storm water management.

Right now I have a soak away for my rain water. I have a well for my regular water. No city water/run-off.

I have a large garden, about a 1/2 rai green area. Does it make sense to collect rain water in my case ?

I'm thinking when it rains, I don't need the water, so I would have to put one or two really large tanks under

ground. I'm thinking 5-10K liters (total) ... I have no idea how long that would last. Bus cost wise, it's the

same as pumping the water from the well (ok, almost). So what would be the justification for this ?

Thanks,

luudee

5K-10K litres isn't much water if you're going to be using it for irrigation - that would only be about 1 week or so of watering for 1/2 rai of well maintained lawns & gardens.

I'd say not worth it.

[Morakot]

I'm thinking when it rains, I don't need the water, so I would have to put one or two really large tanks under

ground. I'm thinking 5-10K liters (total) ... I have no idea how long that would last. Bus cost wise, it's the

same as pumping the water from the well (ok, almost). So what would be the justification for this ?

5K-10K litres isn't much water if you're going to be using it for irrigation - that would only be about 1 week or so of watering for 1/2 rai of well maintained lawns & gardens.

I'd say not worth it.

This is very interesting!

I have estimated if I harvest all my rainwater runoff about 20K L per year and would invest 10,000 baht for a 10K L tank installation, it would take about thirty (30!) years for the investment to start making profit financially. This is based on potentially reducing my current water bill by using 20K L of rainwater per year for flushing toilets and running a washing machine, as well as assuming that the current water prices will stay the same.

Of course if prices increase or one has already some infrastructure in place, than it would be a different matter.

Edited May 31, 2013 by Morakot

[IMHO]

I'm thinking when it rains, I don't need the water, so I would have to put one or two really large tanks under

ground. I'm thinking 5-10K liters (total) ... I have no idea how long that would last. Bus cost wise, it's the

same as pumping the water from the well (ok, almost). So what would be the justification for this ?

5K-10K litres isn't much water if you're going to be using it for irrigation - that would only be about 1 week or so of watering for 1/2 rai of well maintained lawns & gardens.

I'd say not worth it.

This is very interesting!

I have estimated if I harvest all my rainwater runoff about 20K L per year and would invest 10,000 baht for a 10K L tank installation, it would take about thirty (30!) years for the investment to start making profit financially. This is based on potentially reducing my current water bill by using 20K L of rainwater per year for flushing toilets and running a washing machine, as well as assuming that the current water prices will stay the same.

Of course if prices increase or one has already some infrastructure in place, than it would be a different matter.

Doesn't sound like your numbers there have factored in the cost to run, or buy (and replace another 2 times in 30 years) a pump?

I can't see any way such a system could be cost effective - however, if your mains supply isn't reliable that might be a good reason to do something like this

[bunnydrops]

Other--- tank storage for utility (toilet, garden) then into pond

[Greenside]

Your thread came at an opportune moment. This morning we had a meeting to discuss the details of surface water management on our land which will have two houses on it when the current one is finished at the end of the year. The total area is 2.75 rai of sandy soil which very gently slopes to one corner and will be mostly grass but with an access road of some 1000m². The area is prone to flooding but our plot isn't (or least hasn't in the two last bad years in Chiang Mai) and even after heavy rain the water in the lowest spot only stands for perhaps 6 hours before seeping into the ground.

The landscape guy is proposing a simple, but I'm thinking needlessly expensive solution, which is to raise the lowest parts of the plot and run the water to the public road in a small drainage channel that would run alongside the new access road we have to build. I haven't had a survey done to check the exact levels but I bet there won't be much change from 100k and my budget is just suffering from the shock of the cost of the road. Another problem with this idea is that the drain in the road is really only a gutter type and I don't know how effective it will prove to be if we add our water to it.

My original idea was to put several soakaways in appropriate positions and direct water to them with whatever means (French drains, perhaps?).

In the above plan A is the highest point and D the lowest with about 50cm difference and B & C are somewhere in between. E is about 25cm above D and the distance A to E is 130m. Your thoughts and suggestions are most welcome on this.

[thaibeachlovers]

I voted 'other' our runoff from the house is piped directly to the khlong which in turn goes into the river.

Rain that falls on the garden is used by the plants.

Same answer for me.

[Morakot]

Hi Greenside,

Thanks for posting this. An interesting problems!

Like you, I find the proposed landscape idea highly questionable. Two points:

• Stormwater from buildings: I agree a decentralised approach would be the best; French drains connected to soakaways for each building. Plus possibly a storage tank, for your garden. Leading the water away from the land, especially since you have grass-covered sandy soil and this is not flood-prone, does not make any sense IMHO.
• Stormwater from roads: If D is the lowest point than there might be a problem with the run-off from the road from all three sides towards point D. The main question would be what kind of surface will there be rather than immediately looking for raising the area. With a proper Subgrade/ Subbase/ Base/ structure you can have porous pavers (e.g. crasscret or truckpave) on top, which will not require a road drainage system, but significantly reduce the excess run-off. Here an example: http://www.terram.com/products/porous-plastic-pavers/truckpave-porous-paving.html

Edited June 14, 2013 by Morakot

[thaibeachlovers]

Your thread came at an opportune moment. This morning we had a meeting to discuss the details of surface water management on our land which will have two houses on it when the current one is finished at the end of the year. The total area is 2.75 rai of sandy soil which very gently slopes to one corner and will be mostly grass but with an access road of some 1000m². The area is prone to flooding but our plot isn't (or least hasn't in the two last bad years in Chiang Mai) and even after heavy rain the water in the lowest spot only stands for perhaps 6 hours before seeping into the ground.

The landscape guy is proposing a simple, but I'm thinking needlessly expensive solution, which is to raise the lowest parts of the plot and run the water to the public road in a small drainage channel that would run alongside the new access road we have to build. I haven't had a survey done to check the exact levels but I bet there won't be much change from 100k and my budget is just suffering from the shock of the cost of the road. Another problem with this idea is that the drain in the road is really only a gutter type and I don't know how effective it will prove to be if we add our water to it.

My original idea was to put several soakaways in appropriate positions and direct water to them with whatever means (French drains, perhaps?).

In the above plan A is the highest point and D the lowest with about 50cm difference and B & C are somewhere in between. E is about 25cm above D and the distance A to E is 130m. Your thoughts and suggestions are most welcome on this.

Having used soakholes in the past, that would be my first choice.

I used a 1 foot diameter hand auger with extensions to go down to the water table, which was about 20 feet in my case. I filled the holes with small stones.

Cost- rental of the auger, though in LOS probably buy one, as haven't seen any rental places here.

[Gsxrnz]

I'm thinking when it rains, I don't need the water, so I would have to put one or two really large tanks under

ground. I'm thinking 5-10K liters (total) ... I have no idea how long that would last. Bus cost wise, it's the

same as pumping the water from the well (ok, almost). So what would be the justification for this ?

5K-10K litres isn't much water if you're going to be using it for irrigation - that would only be about 1 week or so of watering for 1/2 rai of well maintained lawns & gardens.

I'd say not worth it.

This is very interesting!

I have estimated if I harvest all my rainwater runoff about 20K L per year and would invest 10,000 baht for a 10K L tank installation, it would take about thirty (30!) years for the investment to start making profit financially. This is based on potentially reducing my current water bill by using 20K L of rainwater per year for flushing toilets and running a washing machine, as well as assuming that the current water prices will stay the same.

Of course if prices increase or one has already some infrastructure in place, than it would be a different matter.

Doesn't sound like your numbers there have factored in the cost to run, or buy (and replace another 2 times in 30 years) a pump?

I can't see any way such a system could be cost effective - however, if your mains supply isn't reliable that might be a good reason to do something like this

No the idea is definitely not cost effective - so since we're in Thailand it's the perfect thing to do.