Fuel Storage Tank

[Corey Friedman]

Hi Codeman,

I hope all is well. Here's the scoop.

An underground diesel fuel storage tank used for a legally required standby generator has failed. A temporary above ground disel fuel storage tank will be installed for the generator while the underground tank is removed, ground cleaned up and a new tank installed. The length of time this will take is unknown.

The temporary above ground diesel fuel storage tank is 500 gallons and has two temporay rubber hoses running between the storage tank and the genny.

The distance between the temp storage tank and genny is approx 5 feet. Distance between storage tank and building is approx 35 feet and distance between storage tank and a Com Ed transformer (size unknown) is approx. 15 feet.

Several questions for you.

1. Thoughts on distances.
2. Your take on NFPA 1 Chapter 66 as it applies to this.
3. Would you agree that the flash point for diesel is approx. 143 degree F making it a Class III A combustible liquid.
4. Thoughts on grounding / bonding.
5. I don't have NFPA 30. Thoughts on significant issues from NFPA 30.

As always, your insight is greatly appreciated.

Thanks,

Corey

[Jerry Peck - Codeman]

Hi Corey,

I'm going to try working my way through and see if my thoughts lead anywhere.

An underground diesel fuel storage tank used for a legally required standby generator has failed. A temporary above ground diesel fuel storage tank will be installed for the generator while the underground tank is removed, ground cleaned up and a new tank installed. The length of time this will take is unknown.

First, one code that applies electrically is the NEC (using the 2008 NEC for references) ARTICLE 701 Legally Required Standby Systems, then perusing through beyond the installation of the electrical equipment aspect because it will be presumed that the legally required standby system was already installed and meet all required code at the time of installation, I first go to 701.5 Tests and Maintenance for Legally Required Standby Systems and inquire (rhetorically) about all written records for testing and maintenance having been kept and made available, etc., then on to 701.11 Legally Required Standby Systems, (B) Generator Set, (2) Internal Combustion Engines as Prime Mover. Where internal combustion engines are used as the prime mover, an on-site fuel supply shall be provided with an on-premises fuel supply sufficient for not less than 2 hours’ full-demand operation of the system - and inquire (again rhetorically) about the chosen 500 gallon size of the fuel tank as being sufficient for that requirement.

The temporary above ground diesel fuel storage tank is 500 gallons and has two temporary rubber hoses running between the storage tank and the genny.

Here I question the use of temporary rubber hoses. I would feel better if the fuel delivery system were rigid piping with a flexible section to the generator for vibration purposes, but avoiding the long rubber hoses between the fuel tank and the generator for physical damage protection concerns and leakage concerns. It would be relatively easy to provide containment of a leak at a flexible section/connector such that a small fuel supply leak would not readily become a large un-contained fuel spill resulting in a contaminated area around the fuel tank, fuel supply lines, and the generator, making an already contaminated area more contaminated and potentially larger in scale. I address this as you stated that the distance between the above ground temporary tank and the generator is only approximately 5 feet which seem close for fuel spills between the remote tank and the generator.

I am aware that many generators have self-contained tanks, or are mounted on top of their tank, however, my concern is based on an unknown: what is the distance from the underground tank being removed and the generator and temporary fuel tank? Does the location of the temporary fuel tank provide complete access to the removal site without having to be relocated as removal and decontamination work progresses?

If there is sufficient separation from that removal and work area, then the 5 foot separation between the tank and the generator may be sufficient, which would negate some of my concerns with the rubber fuel hoses.

The distance between the temp storage tank and genny is approx 5 feet. Distance between storage tank and building is approx 35 feet and distance between storage tank and a Com Ed transformer (size unknown) is approx. 15 feet.

Is the temporary fuel storage tank a double lined tank? Probably is.

Is there going to be or has there already been a containment area placed around the generator and the above ground fuel storage tank? Under it to prevent further leak contamination?

Several questions for you.

1. Thoughts on distances.

What are the distances to the property lines? Presuming those distances are acceptable as this is an existing installation, however, the distance of the above ground fuel oil storage tank may not comply with a distance from property lines.

Is the temporary above ground fuel tank over or near the underground service laterals from the power company transformer and from the generator? With the fuel storage tank now being above ground, if there is a leak there is the real potential for diesel fuel to migrate to the underground conductors, are those underground conductors suitably diesel fuel resistant regarding their insulation? If there is a containment system placed under and around the above ground storage tank, that should not be as much of a concern. I know, we are almost 100% positively talking about a double wall tank with the inner space between the walls designed to provide sufficient capacity to hold the contents of a full inner tank without leaking, I am just considering the potential for leaks outside the containment tank of the double wall tank.

The distances in Tables 66.2.3.2.1.1(a) and (b), without having NFPA 30 for reference for "Protection from exposures" are such that the 35 feet to the building should not be a problem, and the minimum distance to the property line should be 20 feet for no protection, if less then it would depend upon the protection provided, which could allow for that distance to be 10 feet (referencing a property line adjacent to property which could be built upon), or half those distances to any public way or nearest building on the same property (not that this states "building" and not "structure', typically a "structure" is anything man made, even the containment for the storage tanks, while typically a "building" is a "structure" which is intended for human occupancy of any type).

2. Your take on NFPA 1 Chapter 66 as it applies to this.

In reviewing NFPA 1 Chapter 66 it does apply to this fuel and use, however, like many NFPA codes and standards it refers to other NFPA codes and standards, of which I do not have all of them. See distances above.

3. Would you agree that the flash point for diesel is approx. 143 degree F making it a Class III A combustible liquid.

Where did you get that flash point information from? I've searched and looked as multiple MSDS for different diesel fuel from different suppliers and they all just said >125 degree F. I then found this site ( http://www.engineeringtoolbox.com/flash ... d_937.html ) which lists common fuels and their flash points and it shows diesel in three grades ranging from 100 degrees F to 125 degrees F (indicating that those two are not what is referred to in the MSDS I found), then one grade which has a flash point of 130 degrees F, which does correspond to the >125 degrees F on the MSDS I looked at.

Thus the information I found indicates it could well be a Class II Combustible Liquid.

I recommend you contact the fuel supplier and have them provide the precise data and MSDS package for the exact fuel being supplied - or is that where you got your flash point from?

4. Thoughts on grounding / bonding.

I would definitely bond the metal tank to the generator frame/ground, if for no other reason than to avoid potentially dangerous static discharges which could ignite the fuel under certain conditions.

5. I don't have NFPA 30. Thoughts on significant issues from NFPA 30.

Like you, I do not have NFPA 30 either, thus I do not know what it requires or allows.

Which gets to a pet peeve of mine: Being as "building codes" are mandated for use by state or local laws, and all state and local laws are the property of the public, then I believe that each and every single code or standard should be available to the public in some form which is printable and copyable, such as on-line. Some codes are available on-line, however, they are not truly public documents if the public cannot print or copy them page by page.

That does not mean the entire document needs to be on-line in a nice booklet pdf file which allows you to print the entire document at one click (however, that would be nice as the "information" belongs to the public regardless of who owns the copyright for it as it is a public document and its use is mandated by public law), but at least on a page-by-page basis to allow the public to use what is mandated.

Those companies would still sell their printed and electronic copies for those who do not want to spend their time printing page by page by page for 300 plus pages or however many pages there may be, they think about the time, the paper cost, the ink cost, and the non-bound hard to use aspect and prefer professionally printed and/or electronic copies (I try to get both the printed and the electronic copies), but for one off uses and references for mandated codes and standards, printing one page here and there or just reading a page here and there would be greatly beneficial.

Off that pet peeve now.