Septic Tank with Drainfield or Small Tanks?

[sammyg]

Trying to find out if anyone has any experience with qualified septic system design used in Thailand specifically Udon Thani area?I have seen many articles about small holding tanks for each individual toilet and sinks,showers and basin waste but they would fill up very soon I would think.Then you would have to have them pumped quite often.I would like to know if any of you have had experience with septic drain field systems there and were you can get the materials concrete septic storage tank with built in dividers?Do you have to make your own,etc.Do they have above ground drain system like they are going into the U.S. or just what most folks do for this part of new house construction?Thansk for your imput!SammyG

[fremmel]

The tanks that you've seen here aren't really holding tanks. They're soak-away tanks. Basically a stack of rings with open joints and no bottoms. You can buy real septic tanks at all the HomeMarts, Globals, etc, but I've never seen drain field pipe. I made my own when I built my drain fields.

This is a common topic on some of the more building oriented sites like , CoolThaiHouse, ThaiVisa and, if you don't mind the noise, TeakDoor. You might find more info there.

[bluejets]

Have a look here.... might be of some help.

http://www.inspect-ny.com/septbook.htm

[sammyg]

Thank you guys very much!Bluejets the above referenced website is fabulous and explains about anything a person might want to know about Septic Systems!It is not specific to the region but you can make it apply to just about any region I would think.Although I was interested in what most Falang type people built in there own homes they had built specifically and to see if the local contractors in Udon Thani had any idea about building septic systems with drain fields?Realizing that the climate is dry there I would assume the waste would evaporate quickly but with most land having to be filled and only about 3' of fill at that above the rice fields water table didn't know how well a drain field might drain say during the rainy season and experiences most folks have had?Maybe most folks use the concrete rings with open bottoms like Fremmel mentioned and if so why and how often they had to have them cleaned out and the smell? I know its not a popular subject but one that is very important when considering building a home unless you live next door to a Thai Gas Station and I can't get back up when I set down on a Thai Toilet and my Pants keep getting all Wet and Muddy on the Outside Too!!!SammyG

[bluejets]

Rainfall here about 40 inches a year (1000 mm)
Apart from that there is another section covering wet areas and you can find it here.
http://inspect-ny.com/septic/septalts.htm

I can see how you may have a problem being 3' over the water table but some form of transporation area should get over that. I'm sure they will cover the subject in the site. Transporation areas normally require a fair area of land though and I don't know if you have much to spare. Usually they are around 100 sq metres over here. Sand base and grassed over but have also seen older types with trees and shrubs that suck up the water.

There is a lot of other good information on the main site covering everything from electrical to A/c, heating, ventilation, structure...goes on and on. Might be useful to other house related queries as well.

[bluejets]

Rainfall here about 40 inches a year (1000 mm)
Apart from that there is another section covering wet areas and you can find it here.
http://inspect-ny.com/septic/septalts.htm

I can see how you may have a problem being 3' over the water table but some form of transporation area should get over that. I'm sure they will cover the subject in the site. Transporation areas normally require a fair area of land though and I don't know if you have much to spare. Usually they are around 100 sq metres over here. Sand base and grassed over but have also seen older types with trees and shrubs that suck up the water.

There is a lot of other good information on the main site covering everything from electrical to A/c, heating, ventilation, structure...goes on and on. Might be useful to other house related queries as well.

[aznyron]

good topic I had a septic system in Tombstone AZ and to be honest I liked it better than when I was hook up to sewer
NO Cock roaches when i went away for a long time they come up through the drains when they dry out
Sammy when using a toilet give the cleaning lady 5 or 10 baht to open the handy cap toilet that what I do
getting back to septic system to find out if you have a good drainage you need a perk test and I do not know of any one who can do that service as well as leech line and leech field I had some limited experience with septic systems
they are easy to build if you can buy the material you can even use plastic water tank

[sammyg]

Thanks Ron and Bluejets appreciate the suggestions and webistes.Was mostly intereseted in what the majority of the farang folks used when building their own houses in Thailand but maybe I am mistaken and most folks around Udon live inside housing areas with many houses and have sewer available or on some type of community septic system?We have I would guess 3' to 4' of fill for about 2 years now settled and an area of about 2 rai total so I should be able to put in a conventional septic system w/drainfield even if I have to drill plastic pipe and cover with some type filter cloth and then see if I can find round drain rock there and then more filter cloth before backfilling.I had hoped that some or most Thai builders were aware of these type of drain fields or would no someone that does but I might be asking for to much?I just can't believe that most Thai folks have a sucker truck come to there house every 3 months or so to suck out these talnks ,especially most Farang fellows I would find this unacceptable.I hate to think you were going to have all the family over for a Wedding reception or Barbque (American kind or Thai)an then find out the tliolets are all full and 50 people over?That wouldn't be a pretty site!Especially with the sucker truck driving thru while Barbqueing!Just Want to Make Sure my Ars is Covered is All!SammyG

[stoneman]

We are currently building a new home south of Udon Thani and we will be installing a drain field...40 meters of 4" PVC..can't find the type with holes or slots, so will end up drilling a bunch of holes(If anyone has a source, I am very interested)...The total system includes two septic tanks(one for our bath and one for the kids)...Because of the location, the kids septic tank(800 liters) runs into ours(1,000 liter)...this in turn flows into a 5 ring underground tank..Also flowing into this tank is the gray water from the sinks, tubs and drains..

This then flows into a very large 6 ring tank with a gravel bottom...There is also another 4" PVC that collects all the rainwater from the roof that flows into this tank and will flow out to the drain field..

Might sound a little complicated and "overkill" but I have a 250 sq meter flat roof and I can not take that water off the roof and into surface drains and this seems like the best solution...

Stoneman

[sammyg]

Thanks Stoneman How long or length do you intend to make your actual drainfield and at what depth?It seems to me that you will be overfilling the drain system by including the roof water runoff especially in the rainy season?But maybe you have figured in enough capacity to your last tank and drainfield.It sounds as if you are having to make your own septic system and drainfield which tells me that an actual septic tank with built in baffles and dividers is not available in Thailand correct when you looked for them?Is your ground sandy,gravel loam or clay type material which will not drain the soil very well?Not sure what most of Udon Thani soil type is?Thanks,SammyG

[bluejets]

When you referred to Septic I thought you were referring to toilet waste. Here they tend to keep the waste water from showers, baths and laundry separate from toilet. The grey water from the former is then just pumped to a surface garden area.
Septic is a different subject or so I thought.

[AussieBoy]

.It sounds as if you are having to make your own septic system and drainfield which tells me that an actual septic tank with built in baffles and dividers is not available in Thailand correct when you looked for them?Is your ground sandy,gravel loam or clay type material which will not drain the soil very well?Not sure what most of Udon Thani soil type is?Thanks,SammyG

Septic tanks are available here with baffles/ Stomeman if using 5 rings and they are the large 1mt dia will have 2000lt in the first tank and 2400lt in the second tank, he says he has 40mt of 100mm slotted /holed pipe, but does not say what is under these pipes, maybe he has good soil drainage, sounds very small if the soil is not up to the drainage, The average rain fall in udon is 1500mm a year, with roof area for Stoneman at 250mt2 and let say we have a 25mm rain fall over night or during the day, expect up to 75mm a day on a regular bases, 25mm of rain will produce over 6000lt / 75mm of rain will give you 18,000, So from these calcs you can work out if the system will drain away the water.

To test the soil seepage rate, dig a hole 1mt square, 500mm deep fill it with water, cover it with plastic to stop evaporation, leave it for what ever time check hourly daily till the water is gone, in this case let say it took 24 hours.

Now we have the drainage rate Lt/Hr/mt2 which is 500lts ÷24hr =21lt Hr per mt2. = 21l/h/mt. working on Western standards The average daily high rate of rate of fall in the wet season for udon will be 30mm or 7500lt for the design criteria in 24 hour period, dont for get this is just roof water, 7500lt max inflow rate and 21l/h/mt.drainage rate, that will take if designed right on a 12 hours max drain ratio to meet most western standards, 360 hours for the drain seepage, 12 hours design rules, 360h÷ 12h = 30mt2 of seepage trench, as in Stoneman case he has from my understanding just 1 tank with gravel on the botton, giving him just 0.8mt of drainage, plus the 40mt of pipe, depending on how the 40mt of pipe is layed and type of rubble put around it.

I would say that if a 1mt wide trench x 500mm filled with gravel or course sand , covered with a geotextile to stop the top soil from clogging the drainage, over filled with top soil then seeded for grass, the 100mm x 40mt pipe is layed into the gravel pit, the you should get a trouble free drainage system, of course if the ground seepage is lower than 21lt Hr per mt2 the system will need to be bigger.

In Oz you can not put roof water in to the Septic drainage system, you need to design a system like above seperate from the toxic septic water, in the above case the septic water drain would work on 300lt a day 3 people average, so the fiels drains would not need to be as big.

The soil around udon 10 k out where I am has clay so 1 mt2 of drainage area will disperse/ drain 24lt÷24hr =1lt/h/mt or for the test hole I dug 50lt took 68hours to drain out, the rest was evaperation from the surface area

The Builder has spoken

[AussieBoy]

I will have 225 mt2 roof area on my home when complete, I dont like the soil for my area for drainage, so I will be using water tanks to collect the roof water to use for drinking washing showering, have 20,000 storage in those water jars, 10 jars plus another 30,000lt in a larger tank at a later stage to build, to many home around my area using the seepage system, so I wont tust a well, I rather use the rain water to good use, and over flow from the tanks will go into a a dam, at the back to use on the garden in the now dry season, about 150,000lt ground dam modified soil as we have good clay content.

That is 25 weeks with no rain giving me about 1000lt a day for the garden, just enough to keep the grass green, I have a 600mt2 block with 300mt3 of grass area garden thats 3 lt mt2 a day not much but enough.

My septic system is starting this week, composting thermo dryed air, via a 1000lt spetic tank into a slow water sand filter tanks, and final polishing of the water by glass sand into the dam, should give me Class B septic water for use on gardens lawns and fruit growing, or prior to dispersal into the dam, storage into a tank and chlorine treated for Class A use human contact, which is only 1 step away from Potable drinking water, thats if you want to drink the water that you shitted in, no need here to go any further than Class B, plenty of rain water for the potable water supply

[sammyg]

Thank You Guys for your info.! AussieBoy you seem to have given your drain field and water use Much Thought!We also never put roof water run off into a drain field in the U.S. Some folks do however put a seperate drainfield of sorts ofr there roof drains but nothing as elaborate as as septic drain field more or less a perforated pipe surrounded by round river drain rock.I will definitely use your guide for "perk test" of water drainage over time period though.Sounds as if you have really utilized all the useage of any water runoff at your place and I compliment your conservation.I am also a friend of the earth but not to your extent,nor to your degree as in filtering your afluent water to the extent that you could almost drink it? I hold the line to only drink Good Fresh Beer and I don't drink or eat where I poop! Thanks AussieBoy,SammyG