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Underground Fuel Tank for Standby Gensets
2

Underground Fuel Tank for Standby Gensets

Underground Fuel Tank for Standby Gensets

(OP)
Hi,

Any additional/special requirement if you want to provide an underground fuel tank for the office building's standy gensets?

 

RE: Underground Fuel Tank for Standby Gensets

Lots & lots of requirements.  Check with the local authorities.  Probably don't want to go there once you know all the requirements.

RE: Underground Fuel Tank for Standby Gensets

Double walled tank c/w leak monitoring for a start, the tank vendors can be quite helpful though. As Davidbeach said check with the authorities you will likely change your mind. No doubt driving around you will see lots of old gas station sites where they are trying to suck all the hydrocarbons back out of the ground.
Roy

RE: Underground Fuel Tank for Standby Gensets

The closest I'd come to doing an underground tank installation is to dig a pit that will allow the installation of an above grade tank with its top below surrounding grade.  leave enough room around the tank for inspection and provide a walkable grate over the top to the whole thing.

RE: Underground Fuel Tank for Standby Gensets

Is it advisable to store diesel in those fibre glass tanks normanlly used for water ? Will the diesel react with the polymers ?

RE: Underground Fuel Tank for Standby Gensets

Buy a gen set complete with aboveground dike tank.  This will save everyone a lot of headaches.   

RE: Underground Fuel Tank for Standby Gensets

Diesel needs to go into double wall tanks designed for use with diesel.  Single wall water tanks would be completely unacceptable.

RE: Underground Fuel Tank for Standby Gensets

Thanks David.  

RE: Underground Fuel Tank for Standby Gensets

(OP)
but do you still need a double wall tank if it is underground?

RE: Underground Fuel Tank for Standby Gensets

Double wall would be just the beginning if underground.  There's a reason that new underground tanks are very few and very far between.

RE: Underground Fuel Tank for Standby Gensets

arnolga:

Anything other than a factory built fuel tank in the base of the generator unit, shall be designed by experienced mechanical engineer familiar with fule systems and codes. It is way beyond capability of any electrical engineer. So let the experts handle it, contact your mechanical couterpart or hire some one.

There are several reqquiremetns in NFPA plus the environmental regulations, spill containment and lots of other things.

 

RE: Underground Fuel Tank for Standby Gensets

Have you considered just using Natural Gas?   

Keith Cress
kcress - http://www.flaminsystems.com

RE: Underground Fuel Tank for Standby Gensets

The other problem you have when the diesel fuel tank is below the engine is getting the fuel up from the tank to the engine.  The height (when tank fuel level is at its lowest....!) from  lower tank level to engine has to be less than the engine pump lift level.

The way round this is to put a day tank in the engine room (bunded) fed by an electric pump from the main tank.  Then you are increasing the complexity and reducing the reliability.

itsmoked - natural gas can be used, but the engines are more complex (less reliable [before any one jumps on me, this is because they are usually designed for continuous operation and have more protection than a simple diesel engine]) and the gas gives an additional safety issue.....  Beacause the gas is usually piped from the utility and not stored on site, then there is always the risk of a supply interuption.

By the way, avinolga, do you mean underground as in buried in the soil (a real no-no in most places now, as others have said) or do you mean in the basement?  Depending on your local codes, you MAY be able to put a bunded tank in the basement.  There are so many issues, you really need a local expert to advise you

RE: Underground Fuel Tank for Standby Gensets

He has posted a plan drawing in another thread. The proposed location for the tank is under the road adjacent he building

RE: Underground Fuel Tank for Standby Gensets

Have you actually read all these responses of which most point out reasons why buried tanks are greatly frowned upon in this century by any modern country?

Tanks leak eventually.

A small leak can pollute a HUGE amount of ground water - damaging entire aquifers!  This of course makes the tank owner financially responsible.
 

Keith Cress
kcress - http://www.flaminsystems.com

RE: Underground Fuel Tank for Standby Gensets

(OP)
Thanks

The set-up of the fuel tank can be such that the leak will be isolated to its location only, if possible.  

RE: Underground Fuel Tank for Standby Gensets

I've been the engineer on a few UG tank projects recently. In most areas of the U.S., it's not all that difficult if you use double-wall FRP with appropriate leak detection. They are expensive. By far the easiest configuration is an outdoor genset enclosure with a double-wall base fuel tank. In a few areas (one big city in the southeastern U.S., and another in Texas) the fire departments are up tight about above ground tanks to the point where UST's are easier. Some jurisdictions require AST's to be fire rated. AST's may require a spill prevention control plan (SPCC).

I can't emphasize it enough - carefully determine the applicable codes and READ THEM, carefully. Then consult the local fire dept (may be city, county, state or any combination of those) and state environmental authority.  

RE: Underground Fuel Tank for Standby Gensets

alehman

Will diesel react chemically with FRP tanks over a period of time ?

RE: Underground Fuel Tank for Standby Gensets

(OP)
thanks, Alehman. Mentioning the spill prevention control plan is worthwhile. Will require this also.

RE: Underground Fuel Tank for Standby Gensets

So far as I know FRP is considered permanent for petroleum products. In the U.S. it seems like most new petroleum UST's are double-wall FRP.

RE: Underground Fuel Tank for Standby Gensets

Thanks alehman.

RE: Underground Fuel Tank for Standby Gensets

In response to Keith's comment, U.S. federal regs require many UST owners to have the financial means to help pay for the costs of corrective action and third party damages caused by a release from their underground tank. Sometimes this is in the form of a UST insurance policy or participation in state cleanup funding programs. This is getting beyond my area of knowledge. Obviously it's not a total solution.

UST's got a bad reputation when so many single-wall steel tanks installed in the 1940's through the 1970's corroded and leaked. I think FRP has proven to be very reliable. Some states (e.g. Florida) now prohibit single-wall UST's altogether and are requiring their replacement whether or not they leak.

RE: Underground Fuel Tank for Standby Gensets

I think it was the late 80's when EPA regulations came out regarding UST's and in Ohio, the state fire marshall's office enforces the regulations.

Don Phillips
http://worthingtonengineering.com

RE: Underground Fuel Tank for Standby Gensets

Enforcement seems to vary a lot. In Michigan, the Dept. of Environment enforces the fire codes. Go figure...

RE: Underground Fuel Tank for Standby Gensets

Arvinolga,

You did not mention the system size, but the choice of tank style will be very dependant on how much fuel you need.  If this is an office building as you state, then I imagine the system is quite small.  If the genset size you need only needs to feed egress lighting and egress pathway lighting for 90 minutes, then you can probably get away with a packaged system utilizing a skid mounted tank below the genset, or at worst case a concrete, dual walled, fire rated tank such as made my "ConVault".  Althought that does introduce pumping and piping, monitoring and spill control. Which will involve Mechanical and Civil/Architecural design.

If the syatem is large, such as one we are currently involved with.  Which is the second phase of the construction of a generator plant feeding a large hospital complex in Los Angeles, California.  The initial phase included three-2MW gensets, with diesel fired engines generating at 12 kV.  We are in the process of adding two more.  These are on a closed transition switching scheme with the utility which will be adding a 66 kV-12kV substation.

The site is extremely crowded, there would be no room for above ground storage and having 100,000 gallons of diesel fuel in tanks above ground is not only a physical and safety concern, it is an eyesore the County and the Architect would hang us for.  The initial two tanks are underground and have presented no problems whatsoever.  We have dozens of installations using Underground tanks.  The leakage monitoring of the interstitial spaces, fuel piping, man-wells, etc..., is a well regulated and common installation.

Our Mechanical/Plumbing engineers are well versed in fueling systems, the piping, pumping, monitoring and fuel management systems are part of their daily routine.  I suggest Arvinolga, that you contact a local Mechanical consultant and hire him to assist with the design.  It is very possible to get a depandable, safe, environmentally friendly design with underground tanks.

RE: Underground Fuel Tank for Standby Gensets

To summarise my local (Aus) requirements, you need the following for USTs at least:

-Double walled tank w/ interstitial monitoring.
-Double walled pipework (incl. vent, fill, etc) w/ interstitial monitoring on wet legs.
-Monitored transition pits where joining with single walled pipe.
-All monitoring able to detect 0.76L/hr product loss.
-Pit inspection well.
-Geotextile pit lining.
-Regular statistical inventory reconcilliation.

Like others, I'm frequently faced with needing 30,000L+ of diesel and nowhere to put it so unfortunately have to bury my FRP tanks also.  In my experience, vendors will warrant tanks for 25 years and more assuming not greater than E20 biofuel mix.  

One final note on FRP - choose your installer carefully as there the risk profile is greatest during install (transporting, handling, alignment, bedding, etc) as opposed to steel tanks whose risk tends to build with time from corrosion. Most FRP vendors should operate an installer accreditation scheme to suit.
 

RE: Underground Fuel Tank for Standby Gensets

(OP)
thanks everyone!

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