Urgent, Please Help Provide Aid To Poor Guatemalans

bkhan90

I like this idea (sorry if yall have been saying this all along). so if I pour a reinforced slab I could set the tank on it? Are footings necessary?

Mike Finley

A rotoplas will eliminate some of the water contamination issues and is considered a bit more sanitary then a concrete cistern, I believe. But the bigger issue would be the lack of construction expertese to build the tank which would be more difficult then simplying buying and transporting a plastic tank.

tgeb

No footings are not necessarily necessary.

You have no frost concerns, the slab can be strengthen (if needed) using grade beams. Or simply reinforced below the bearing points of the tank.

Seismic concerns are something else altogether. You may have some work to do in that area....I don't know what zone that area is in.

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Tom

www.gebcon.com

Mike Finley

Footings wouldn't be required because the load transfer isn't around the edges like a house. The load transfer will be even under the tank itself.

This is why I have been asking you why the tank needs to be elevated, a slab would be a simple thing for you to build onsite and require very little construction/engineering knowledge. A slab is a slab pretty much and thicker and more rebar will always help overcome most problems.

Just follow your excavation and tamping plans, load it with a rebar grid and build it 12 inches thick.

bkhan90

Exactly, I don't even know how you would begin to pour concrete in that shape. Also we don't have much time in Guatemala per trip (this trip will be 16 days) so building the forms shouldn't take us much time for simple objects, but for the structure that Willie showed it would probably take us while. I think the idea is a good one, no doubt, but that our lack of expertise, resources, and time makes it more reasonable to simply buy a tank and mount it on a structure.
Thanks

tgeb

A plastic/fiberglass tank would also be more forgiving and less likely to leak if there were to be a settling issue or an earthquake.

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Tom

www.gebcon.com

bkhan90

I submitted the idea to the project lead, it seems very reasonable. Would footings help stability in terms of rain/erosion?

also if someone could tell me if there tried and true methods for draining the excess water from curing concrete via flooding i'd appreciate it. I was just plannin on digging a path then removing the dirt wall of the damn so the water would flow out.

edit: also if we are putting rebar in the base (the pattern is described in the pic) how thick would the slab have to be (I know it's difficult to guess without soild numbers, but I don't have those, I'd have to email another team member).

Mike Finley

That's a very good point.

bkhan90 - Id also recommend you cure with the plastic sheets and avoid the water flooding method. In a high humidity place where you are going to be it will be relatively simple to use plastic.

I don't see any benefit to footings for erosion. You should control the erosion issues by dealing with the land around the slab area with ditches or something to divert rainwater away from the slab before it gets to it.

Remember to try to slope the top of the slab slightly, just good building process to allow the rain water to run off of it instead of pooling.

tgeb

The best way to avoid erosion issues is to make sure that water drains away from the area in all directions.

As far as the water cure for the concrete, you are probably on the right track, with the dam, but you can also keep the slab wet with burlap or straw soaked periodically through out the day.

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Tom

www.gebcon.com

bkhan90

I like the dam because I am sure we can get some water. I don't know if there will be burlap/straw available though I'm assuming its quite common. I read on the internet that curing via flooding produces the strongest concrete, is that incorrect? Also if I do decide to flood, how do I get rid of the excess water after curing?

tgeb

Flooding may be an exaggeration, you simply need to keep the concrete wet and as cool as possible. I would not make the pooling of water over the slab a major concern. Find a way to keep it wet for a few days....you should be good.

My main concern would be the availability of quality concrete.

If you end up building a dam around this, you will have to remove all of it; as per the drainage recommendations above.

I would get the pump system in place first, then work on the slab forming and pour. Once the slab is set enough for water to go on it, turn on the pump and spray away your worries.

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Tom

www.gebcon.com

bkhan90

Yea, I don't think there's gonna be a pump available, so maybe plastic covering is the best bet? I was planning on like dumping buckets of water on the concrete.

tgeb

Where is this pump and solar panel?

When is it being put in place?

You are not planing on a 16 day vacation to just set the tank are you? Could be you have the cart in front of the horse, the tank is useless with out a means to fill it.

For that matter if there were only money for one phase of the project, I would do the pump first, at least these people could get some water, if only during daylight hours.

What is the plan here exactly?

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Tom

www.gebcon.com

bkhan90

This trip is to pour the cement structures and gather information for the weir (the materials necessary), the piping path up the ravine, and the layout of the solar panels. We feel it is necessary to do some work as the community is losing faith in EWB as an irresponsible member a few years ago promised the project would be done in one year and then quit the team. The objective is not for us to implement anything except the concrete structures because neither the community nor the nearest rotary club has been able to provide us any information that we desire. Also, I'm not really in a position to call the shots in the team, I'm only a freshman, so I really can't do much aside from the tasks I've been provided. So, yes we are laying the base for the tanks on this trip (not the tank it self) without actually puttin in the pump, weir, solar panels, and chlorination system but within the circumstances its what we feel is necessary
Edit sorry profanity

tgeb

Well good luck with it, it sounds as if you may have an uphill battle as far as getting everything coordinated and then put in place.

Let us know how things work out.

Feel free to post any other questions, there is quite a bit of real talent on this site and some very intelligent guys.

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Tom

www.gebcon.com

bkhan90

Well the idea of excavating around the tap and putting the tank on just the slab got shot down, I offered it at the meeting today and they shot it down because they said we were too far into the project to change the design. Another question I have is that if I slope the slab how would I do it? I was thinking I could just slope the form, but idk if concrete is viscous enough to keep this shape when poured, or will it flow out? i was thinking of making one side 1" higher than the other. Also, can you guys direct me to some good reading on how to allow for drainage around the slab, it turns out no one has considered this yet so I'll do it.
Thanks agai for all the help!

oldfrt

It seems your doing a lot of leg work for this project,and getting shot down for your suggestions.
Kudos to you for your effort,at least your doing the research necessary before handand not commiting your acceptance to the proposed design.

I can't give you an answer to your sloped slab ?,but someone here probably will.

Keep up the effort,it'll get you where ou want to be..............eventually!

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Willie T

Slope is no problem with a light enough slump. No problem at all. Just walk out to your driveway and look. And if your curbings in your city are like most suburban areas, you'll find severely sloped curbing everywhere. Even right in the heart of the city, 4" slopes in the space of three or four feet are poured daily at intersections for ADA compliance. Look at the many businesses in your city that have handicap ramps.

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Bill Everett - St. Petersburg, FL

tgeb

As far as slope on the slab, I would make the high point run down the centerline of the tank. Set the perimeter forms level along the sides, with about 1" rise to the center. Much like the crown in a roadway, or the pitch of a roof.

Once the forms are set, pull some string lines across the form and set grade pins 5' or so apart and screed to these. The concrete will hold that much slope easily.

For drainage I would say at least 1/2" per foot, for a minimum of 5 feet away from the concrete pad.

Make sure the tank pad is placed in an area that is not subject to run off from other areas. You don't want a rogue monsoon rain eroding around the tank.

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Tom

www.gebcon.com

Willie T

Guatemala is no different than many countries in that they do extensive masonry work all the time in the construction of structures even in a village like you're talking about.

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"True eloquence consists in saying all that is necessary, and only that which is."
François Duc de La Rochefoucauld
Bill Everett - St. Petersburg, FL