Water Tank Base Construction

[alefgard]

Hi,

 

We are going to install a 1,000L water tank at the back of the house and we plan to build a concrete base to put tank on top and address potential land subsidence.

I'm not very familiar with this kind of construction and asked quote from some local construction team.

They quote us 10,000 baht for 2x2 sqm base with 4 micropiles. They said they will install the micropile about 2 meter deep.

Can I ask if the depth of mircopile is enough or should be deeper? Is 10K a reasonable quote for labor + material?

[HashBrownHarry]

I don't know the technical side of this but 2m deep sounds way over the top.

 

I've done this a few times with a 1000ltr tank, concrete depth only about 8-10" ( with re-bar ). Also 2m x 2m sounds big unless you're going to mount a pump on this base as well?

 

Others with more knowledge i'm sure will have input but this is just based on what i've done in the past.

[Boomer6969]

Your base is likely to be heavier than the tank itself. 1000L isn't a heavy load.

Also keep in mind that if you install your tank near a recent construction there will be a subsidence differential between the the micropiles nearest to the house and those 2 meters away. 

I'd just go for a light iron/smartwood structure set on a temporary foundation that you may readjust as needed.

[Yellowtail]

Not knowing what the OP's ground is like  makes it impossible to determine whether or not piles are needed, or if needed how deep they should be, but I would say that 10K is a fair price for a 2m X 2m reinforced slab that includes four piles. 

 

 

[Crossy]

Ours is on 1m mini-piles (2400L tank), it promptly shifted in the wet season.

 

Removed the tank and just leveled the top and replaced the tank. It's not moved since so we evidently saw intial movement of the land fill. 

 

We are on Bangkok clay (house has 16m piles) and the fill was relatively fresh.

 

As above, we really need to know where our OP is and what his land is like, he could get away with just a 200mm slab if the ground is stable.

[Madgee]

I had a 5m x 1m run of of reinforced cement laid on a 4'' hardcore base by the side of the house. (1000ltr tank and pump to go at the end on a wider section 1.5m)

 

2 guys took 1 day to complete. No boarding required as between house wall and garden wall, just the ends.

Cost: 3000฿ inclusive of all materials.

 

TBH, they done an excellent job and even filled in a few large cracks in the surrounding wall with the spare cement.

This was 18 months ago just after the floods. So far so good.

10,000฿ seems a bit steep to me. 

 

[Tagged]

2m deep? 

 

For a 1000l tank it is ok with 2 x 2 m base, where you start with gravel, sand, iron, and 12 - 15 cm base. It is not to much weight load on that 1000l if you are not in something that turns in to a swamp when rainseason. 

 

 

I did the same here with a 4x4 base, no pilars and I got 2. 6m3 and one 3m3 on it pluss the pumps. The base is 25cm +-

 

Edit note, the corner roof pilars is about 100cm in to the ground. And I paid 9 000,- baht for the work on this one complete with roof. 

 

Edited January 10, 2021 by Tagged

[alefgard]

1 hour ago, HashBrownHarry said:

I don't know the technical side of this but 2m deep sounds way over the top.

 

I've done this a few times with a 1000ltr tank, concrete depth only about 8-10" ( with re-bar ). Also 2m x 2m sounds big unless you're going to mount a pump on this base as well?

 

Others with more knowledge i'm sure will have input but this is just based on what i've done in the past.

Thanks, no pump, it's installed separately on a different side. The house came with an underground tank installed, it's about 8y.o. now and we are going to replace it with an above ground type. With a 1K L tank, what base size should be enough? 

[alefgard]

1 hour ago, Boomer6969 said:

Your base is likely to be heavier than the tank itself. 1000L isn't a heavy load.

Also keep in mind that if you install your tank near a recent construction there will be a subsidence differential between the the micropiles nearest to the house and those 2 meters away. 

I'd just go for a light iron/smartwood structure set on a temporary foundation that you may readjust as needed.

Thanks, house been built for about 8 years now.

[alefgard]

1 hour ago, Yellowtail said:

Not knowing what the OP's ground is like  makes it impossible to determine whether or not piles are needed, or if needed how deep they should be, but I would say that 10K is a fair price for a 2m X 2m reinforced slab that includes four piles. 

 

 

Our village is in Bang phli, Samut prakan, at the back of Homepro/Market village, near the Sarasat school. ???? After 8+ years of construction, the land is still subsiding but at a much lesser rate.

[alefgard]

42 minutes ago, Madgee said:

I had a 5m x 1m run of of reinforced cement laid on a 4'' hardcore base by the side of the house. (1000ltr tank and pump to go at the end on a wider section 1.5m)

 

2 guys took 1 day to complete. No boarding required as between house wall and garden wall, just the ends.

Cost: 3000฿ inclusive of all materials.

 

TBH, they done an excellent job and even filled in a few large cracks in the surrounding wall with the spare cement.

This was 18 months ago just after the floods. So far so good.

10,000฿ seems a bit steep to me. 

 

Thanks, but i guess this 3,000 thb doesn't include any micropiling works?

[Mama Noodle]

Unless youve got some unusual kind of earthwork going on, ive installed 7-8 of these things over the years on nothing more than a 10 cm thick concrete pad right on top of the ground. No piles, no drama. Just a rough form and handmix out of a bucket. 

 

My current 1000l tank is probably only sitting on MAYBE 5cm thick "sidewalk" and hasn't moved in 2 years. 

 

I struggle to see why anyone would need to spend 10k for a single cubic meter of water storage unless youre living in a swamp or clay. 

[uncleP]

You are getting security for $333 What is there to worry about? Our Bangkok house has 2M piles inder our 1200l below ground watertank. Admittedly we are on very wet ground but have had no issues. I spent years doing groundwork as part of being involved in Government contracts for plumbing and heating & to do it once with  built in redundancy is preferable to having to do it again! LET'S NOT FORGET WE ARE TALKING ABOUT $333 NOT $30000.

[alefgard]

11 minutes ago, uncleP said:

You are getting security for $333 What is there to worry about? Our Bangkok house has 2M piles inder our 1200l below ground watertank. Admittedly we are on very wet ground but have had no issues. I spent years doing groundwork as part of being involved in Government contracts for plumbing and heating & to do it once with  built in redundancy is preferable to having to do it again! LET'S NOT FORGET WE ARE TALKING ABOUT $333 NOT $30000.

Thanks, we share the same idea that we'd like to this change and put micropile to avoid adjusting/repairing it again after few years. Do you think 2M piles is enough? Read some comments from others recommending about minimum 3M.. 

[SimpleMan555]

A 1000ltr tank is not a large load, and the correct tank base design will depend on your soil type, (Clay, Sand, laterite etc) and how wet the ground gets in the rainy season. Your proposed plan might be the best option if the soil is clay and it gets wet and soft in the rainy season. To me, 10,000 baht seems like a very high price for the average install, ask for a list of materials and cost for the same. Check the prices yourself to confirm the cost for both labor and materials or purchase the materials yourself.. 

I have seen tanks happily sitting on top of a round concrete ring base with rock-sandy soil underneath and not moving for years...it all depends on your local site conditions. As others have shared, your can do this with a very simple base if the soil will allow and there is proper site preparation.

 

The biggest things I see here with this type of work is the lack of sub-soil preparation and compaction. The soil underneath the concrete base should include a basecourse layer of crushed gravel with fines (12cm +/-) that is compacted using a plate compactor & lots of water. This area should extend outside the area of the tank base (2.5mx2.5m minimum). The area should dry out a bit to let the soil settle and then dig the holes for the piles and add the formwork & concrete.  The slab should have ample re-bar or heavy gauge wire mesh supported with 50mm +/- concrete chairs/blocks to maintain a minimum of 50mm concrete coverage under the metal, (this prevents premature rusting & failure of the rebar).  Sand on top of the gravel is not recommended as it shifts with changes in moisture content, does not compact well, and allows excess wicking of water into the concrete.

 

If you have a drawing and can describe your soil/site conditions it will assist in giving better advice.

Good luck, T

 

 

Plate Compactor:   Commonly found at most large building supply shops and the builders should have access to one...

 

 

 

[sometimewoodworker]

With our 3 x 2,500 litre tanks all I used was sand to level then cinder blocks laid flat no concrete, no rebar under 1,000 Baht. The tanks are under a building so there is rain protection. They have been in place for 4 years now. In our previous house the base was the same without the sand it’s been there for 15 years.

 

Our soil is heavy clay, I don’t say our structure is suitable for you, I do say that your build cost is way OTT 

[Cake Monster]

3 hours ago, alefgard said:

Hi,

 

We are going to install a 1,000L water tank at the back of the house and we plan to build a concrete base to put tank on top and address potential land subsidence.

I'm not very familiar with this kind of construction and asked quote from some local construction team.

They quote us 10,000 baht for 2x2 sqm base with 4 micropiles. They said they will install the micropile about 2 meter deep.

Can I ask if the depth of mircopile is enough or should be deeper? Is 10K a reasonable quote for labor + material?

A 2 x 2 M square base is a little large, but remember, the bigger the Base the less pressure placed on it, and therefore less chance of subsidence.

IMO here is no need for any Micro piles.

Make your Base 2 x 2 M and 20 cm thick with loads of 10mm Diameter rebar throughout in 2 layers

should be more than adequate. This will stop cracking

Costs

Concrete from CPACC or similar 1,900 per Cube M You only need  less than 1 Cube( Better to mix this small amount by hand ) or Possible Mini MIx Truck ????

Approx cost

Sand 250 + gravel 250  =500 Baht

Cement 5 Bags @ 120 + 600Baht.

Rebar 10 Dia x 6 Pcs @ 6 M long = Approx 500 Baht

Labour 

2 guys x 2 Days @ 600 each per Day = 2400 Baht

Ods and sods call it 1000  Baht

Total everything 5,000  Baht ( ish )

Even with Labour at1000 each per day its only 6,600 Baht

This would be about the cost IMO

Ask a Local Building supplier for exactly how much  Sand and Gravel and rebar you need, if they are any good they will not rip you off, and always buy the stuff yourself.

Wait out a while for other Forum members to chip in with their thoughts and ideas.

 

[soumanioco]

[Tagged]

16 minutes ago, soumanioco said:

Yes, and remember to not take of the plastic. 

[tifino]

21 minutes ago, soumanioco said:

all it needs is an Input, for the gods to vent their anger down thru...

 

 

must be a challenge when thai roofs don't have gutters!

[Kwasaki]

7 hours ago, alefgard said:

They quote us 10,000 baht for 2x2 sqm base with 4 micropiles. They said they will install the micropile about 2 meter deep.

A rip off. 

A 2000 Litre tank on clay settled ground,  a 20 cm thick slab 2 x 2 M,   4 steel 10cm x10cm posts,  5 steel 2cm x 4cm roof frame supports and 3 No. 3" standard galv roof sheets 2.5 M long. cost us 3,200 baht.

[Madgee]

Sorry Op but as many say:  You tink 2 mut ! 

Keep it simple.

It's only a small tank and you really don't need to build a launch pad.

My slab (no micro piles) is on unstable ground hence the cracks in the surrounding walls (paddy fields behind) and it's fine. 

Anyway, from my limited experience; buy a larger tank and shield it from direct sunlight is more important. I'm upgrading my tank as finances permit. 

JMO.   

If money is no problem then do what you think fit, it's your money!

 

 

 

 

 

 

[HighPriority]

As always in this place there’s a 1000 different opinions ????

In Australia I’ve just installed a 275,000 Lt tank, no concrete slab, it sits on a pad of “cracker/crusher dust” which is a byproduct of making aggregate used in concrete and gravel. 
The pad is 1 meter wider than the tank (14.5m) and covered with 20-60mm rock to protect the base from erosion by rain, so you don’t need much for your job do you ?
In your case I’d be looking @ putting in a larger slab that will serve another function, after all a 1000Lt tank doesn’t take up much room and it sounds like it could be a useful space for you.