Driving over a buried fuel tank

[jtstruct]

Hi Gang,

I have an unusual situation, and I hope this is the right forum for this thread. We have an existing buried fuel tank in a grassy area (supplying an adjacent above ground generator). Due to limited access in the landscaped area, a truck will have to drive over this tank to access a vault to service the electrical equipment. They only expect to access it once every 20 or 30 years (i.e. "almost" never) with a 20 ton truck. We are considering installing a 6" reinforced concrete pad over the tank and rating the manhole cover for traffic. However, this seems like overkill for the one or two times there will be traffic over this tank during its life span. Are "logging" mats an option for this situation? I'm not too familiar with these temporary mats - how do you specify these?

Thanks in advance for your help.

 

[SlideRuleEra]

Answers to these questions will be the keys to a solution:
1. What is the distance from the top of the tank to ground elevation?
2. What is the tank shape & orientation (cylinder? rectangular?)
3. What is the tank diameter (width)?

Other issues are important, such as tank wall thickness, tank full or empty when loaded, soil properties, etc. However, details on the three questions should be enough information to point toward a solution.

 

[jtstruct]

SlideRuleEra,

Here is some more information:

1) the top of the tank is down approx. 3.5' from the ground elevation
2) it is a cylindrical steel tank, double-walled, 550 gallons
3) I think the diameter is 3'

Typically the tank stays full, and it rarely falls below 50% capacity.

Thanks for your help.

 

[SlideRuleEra]

jtstruct - Given those conditions: If the ground is "solid" enough to keep the truck from getting stuck, you should be ok driving over the tank "as-is". Cheap insurance would be to (carefully) dump 6 or 8 inches of crushed stone or similar material over the existing ground, and leave it to self-compact - does not sound like you need the concrete.

Best Wishes

 

[Ron]

jtstruct...I agree with SlideRuleEra...shouldn't be an issue. Using gravel or other stabilization material will increase the resilient modulus of the subgrade and allow it to help "bridge" the load. For a 20-ton truck and such low frequency over such a small tank, you could just use a few 4x12 timbers to create a driving mat.

 

[jtstruct]

Thanks! I appreciate your time.