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Structural design of water tank 6
- Thread starter Gulmitic
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In a perfect world, there would be no water leaks, no crime, no rusting, no poor soils, everyone would be above average.....
However, this is not a perfect world.
Nobody makes large (greater than 30 ft dia.) buried tanks out of steel or lined plastic. Steel tanks are more commonly designed for atmospheric pressure. Plastic linings are desiged to protect the tank walls from corrosion, not to prevent leaks. This is something that an experienced civil structural would call common practice.
Large buried concrete tanks will settle and crack over a period of several decades allowing minor leakage and contamination into the tank, not out of it.
Unlike a pressurized tank, where the flow is outward, a large empty buried tank will be subject to the same phenomena known as I/I.
You are the second person on this thread to post that the Ten States Standard is a sewer standard. Not sure where you are getting your information:
Article 7.0.2(c) and (d) of the Ten States Standards is not a sewer standard.
However, this is not a perfect world.
Nobody makes large (greater than 30 ft dia.) buried tanks out of steel or lined plastic. Steel tanks are more commonly designed for atmospheric pressure. Plastic linings are desiged to protect the tank walls from corrosion, not to prevent leaks. This is something that an experienced civil structural would call common practice.
Large buried concrete tanks will settle and crack over a period of several decades allowing minor leakage and contamination into the tank, not out of it.
Unlike a pressurized tank, where the flow is outward, a large empty buried tank will be subject to the same phenomena known as I/I.
You are the second person on this thread to post that the Ten States Standard is a sewer standard. Not sure where you are getting your information:
Article 7.0.2(c) and (d) of the Ten States Standards is not a sewer standard.
There are hundreds, if not thousands, of buried potable water tanks in service. Mosr are designed under AWWA standards, State Health Division standards and structural standards of ASCE, CRSI, and others. I have designed dozens, mostly conventionally reinforced concrete, although some pre-stressed tanks exist below grade. Most are placed on hillsides or hilltops where groundwater, if any is present, will flow away from the tank.
They come in all shapes and sizes from a few hundred gallons to millions of gallons. All are leak tested periodically. Some have their roofs exposed and are used for recreation areas such as tennis courts, urban parks, etc.
I have never heard of a case of contamination by groundwater leaking into the tank. If such cases exist they appear to be very rare.
Among the advantages if burying a tank include:
stable temperature in hot climates
no need to repaint or recoat the tank exterior
ease of monitoring leakage into or out of the tank
aesthetics
long life ( some such tanks have been in service without problems for over 100 years)
Burying half the tank appears to be arbitrary and accomplishes what ?
At one time in history, the Ten State Standards were strictly wastewater standards but, it appears, they have grown in scope over the last 40 years since last I looked at them. In Oregon, where I live and work, and in California and Washington the Ten State standards do NOT apply.
None of this answers the original posters question which was about the structural design of such tanks so I apologize to him or her for digressing.
They come in all shapes and sizes from a few hundred gallons to millions of gallons. All are leak tested periodically. Some have their roofs exposed and are used for recreation areas such as tennis courts, urban parks, etc.
I have never heard of a case of contamination by groundwater leaking into the tank. If such cases exist they appear to be very rare.
Among the advantages if burying a tank include:
stable temperature in hot climates
no need to repaint or recoat the tank exterior
ease of monitoring leakage into or out of the tank
aesthetics
long life ( some such tanks have been in service without problems for over 100 years)
Burying half the tank appears to be arbitrary and accomplishes what ?
At one time in history, the Ten State Standards were strictly wastewater standards but, it appears, they have grown in scope over the last 40 years since last I looked at them. In Oregon, where I live and work, and in California and Washington the Ten State standards do NOT apply.
None of this answers the original posters question which was about the structural design of such tanks so I apologize to him or her for digressing.
On the contrary, RWF7437, there is no way you can design a tank without knowing what is going to be stored in the tank, as well as the other particulars such as soil condition, weather, site layout, etc. The original poster provided little of that information.
If the original poster is not sure of how to design a concrete tank, reminders of what codes and standards to follow should be considered friendly advice, not an opportunity to debate others.
For example, if he was designing a concrete oil/water separator, you might refer him to the API. If water, then to the AWWA. If wastewater, then to etc.
The title of the post is actually "water tank". So referring someone to the Ten States Standards for Water is not out of line. While it is true that there are some jurisdictions that do not reference the Ten States Standards, many of details of the Ten States Standards have been copied into the standards of these other jurisdictions anyway.
Re: "ease of monitoring leakage into or out of the tank" How do you accomplish this? One would think that this is more easily done with an above ground tank.
Lastly, it is probably not good advice to recommend that someone pick and choose what standards to follow just because a person doesn't understand the reason for the standard.
If the original poster is not sure of how to design a concrete tank, reminders of what codes and standards to follow should be considered friendly advice, not an opportunity to debate others.
For example, if he was designing a concrete oil/water separator, you might refer him to the API. If water, then to the AWWA. If wastewater, then to etc.
The title of the post is actually "water tank". So referring someone to the Ten States Standards for Water is not out of line. While it is true that there are some jurisdictions that do not reference the Ten States Standards, many of details of the Ten States Standards have been copied into the standards of these other jurisdictions anyway.
Re: "ease of monitoring leakage into or out of the tank" How do you accomplish this? One would think that this is more easily done with an above ground tank.
Lastly, it is probably not good advice to recommend that someone pick and choose what standards to follow just because a person doesn't understand the reason for the standard.
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