Old transformer oil containment

[atrizzy]

Hi all,

I've got a project where a client wants to install a very old transformer (that they got a GREAT deal on I'm sure) and I am in charge of the foundation/oil containment/oil water separation design.

Typically I would design a gravity OWS past the outflow to handle the design flowrate and contain a stop valve at outlet for stoppage of a catastrophic breach.

The client has no appetite for this, however, and has asked why they can't just install a stop valve at the outlflow of the containment pit. My response to this is that for an old transformer, likely to leak as a matter of course, the stop valve may not be sensitive enough to stop minor leaks and we'll likely get some oil escaping.

I also looked into products similar to 'imbiber beads' where even trace amounts of oil should engage the stop valve, but of course with a leaky transformer (and dusty site conditions) the thing would likely always be stopped.

I know I'm asking for a perfect solution here, which may not exist, but I'm curious as to what the group's thoughts are on this issue.

Thanks in advance.

 

[FacEngrPE]

You don't need an oil stop valve, or the oil water separator, the minimum is the dike with the required volume, and a ball stop valve, with a plug in the outlet end of the ball stop.
The down side is that your client now needs competent tradesmen that will drain the water, and not spill the oil manually. Your client should understand and accept the risks of the installation you provide to meet his criteria.

 

[dik]

Have you looked into a product called Sorbweb... I've done about a dozen transformer containment structures using the material. I have no financial connection to the company, but their solutions are very cost effective.

https://www.albarrie.com/secondary-containment/

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[bimr]

Your project appears to be in Canada. Not sure what the oil spill regulations are there.

In the U.S., if the volume of oil in the transformer site is greater than 1,320 gallons, the facility is regulated by the SPCC requirements. You have two options: Option 1 – Provide secondary containment: The first option would entail providing an impervious barrier capable of containing the volume of oil held by the largest single vessel. If exposed to precipitation, the secondary containment would also
need to hold a reasonable amount of precipitation (typically a 25-year, 24-hour event). Option 2 – Implement an Oil Spill Contingency Plan (OSCP): The second option is less disruptive and less costly, as the electrical utility would likely prefer to avoid installing secondary containment at a remote facility. The utility can implement an OSCP that requires the utility to:
• Commit manpower and resources to addressing oil spills/releases
• Monitor the facility for oil spills/releases
• Develop an oil spill response plan


Smaller transformers are not generally provided with containment per se, but one should anticipate where the oil will drain should there be a failure. One wouldn't like to risk a transformer failure that occurs in a location that is next to a river or dock.

Have never witnessed an OWS on a transformer installation. If the transformer is leaking, it should be repaired.

 

[atrizzy]

Thanks all,

FacEngr, what do you mean by 'plug'? Is this something like a sorbweb material or filter that traps trace hydrocarbons?

dik, I don't think I have the space for a sorbweb solution as this transformer contains an immense amount of oil. I'm currently exploring their in-line Q-MAX HF filter type system which appears promising.

bimr, sure, a transformer shouldn't leak... but something tells me it will nonetheless. I'd love to balance the requirements for the operators with the capacity of the system to work passively.

Thanks again for your responses.

 

[dik]

The one transformer yard had 6 'huge' transformers each was the size of a large house. 400K each... Each one had 2-1/2 tanker cars volume of cooling oil. More oil than that? I'm impressed if there is.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

I seem to recall there was a case in BC, Canada, where an engineer was held criminally liable for environmental damage. Best to tread safely...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[atrizzy]

dik, it's the space that's the issue. I don't have the space for the earth berms that would be required to achieve the depth for the containment volume.

 

[dik]

Most of the transformer pads were at grade, with the soil beneath replaced with coarse aggregate with a high void ratio. There were no containment berms. The last one, the pit was lined with an EPDM material and a small 'window' with Sorbweb to allow rainwater to pass. If transformer oil reaches the Sorbweb, it jells into an impermeable material, and closes the window. You might want to talk to them and see if they can assist with a solution... they're pretty good... and there are not a lot of people I recommend...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[atrizzy]

Unfortunately, we have shallow bedrock and need to build our containment up... and our footprint doesn't allow for much berm width.
Perhaps I'm not understanding, but it seems problematic for our situation.

 

[dik]

...and interesting problem. Can you have a small containment with an alarm triggered vacuum system? I've never heard of this being done, but the first thing that comes to mind...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[atrizzy]

I'd rather in that case lead to something highly active (such as a very sensitive plug at the outflow... the Albarrie product I mentioned before) but put more of an onus on the owner to maintain the system, check for blockages, remove any blocked water and replace the active 'cartridges' in the plug unit...

What's your sense on the risk of such an approach?

 

[dik]

My experience is that you cannot rely on that sort of involvement... maybe coupled with an alarm system, if one exists... there should be something positive in place.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

I don't know if there's a means to determine if a transformer is leaking. Any leaks I've encountered (and not many) have been small and slow and nothing catastropic.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[atrizzy]

Agreed... this conversation is getting a little freewheeling, but nonetheless, playing devil's advocate, surely it could be relayed to the owner that they are responsible for ensuring their transformer is free of leaks, and that the containment system is therefore designed to prevent catastrophic spills?

 

[dik]

and a really good 'hold harmless' clause; in some jurisdictions that my not suffice.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dauwerda]

I'm not sure how old a "very old" transformer is, but the sparkies at the utility I used to work at always indicated that the "very old" transformers were built much more robustly and were much less prone to failure than the newer transformers. They said this was due to older transformer designs not having the pencil sharpened to the extent that is capable now.
I also recall that they said if a transformer was in service for more than something like 2 years, chances of catastrophic failure decreased dramatically.

I bring this up simply to make the point that a "very old" transformer is less prone to a catastrophic failure (that would require/benefit from oil containment) than a new transformer.


Most of the containment my former utility utilized was sized to have enough volume for a 10 year 24 hour design storm, the oil, and a few inches of freeboard. Some of the designs included an oil minder pump to remove excess rain water (doesn't pump if it senses oil). Others just depended on evaporation and/or maintenance employees pumping water out of containments after storm events.

 

[dik]

Thanks dauwerda... didn't know they had them.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dauwerda]

dik, attached is a brochure giving a bit more details on the pump(s):

 

[dik]

thanks...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik