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Old transformer oil containment

Old transformer oil containment

Old transformer oil containment

(OP)
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.

RE: Old transformer oil containment

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.

RE: Old transformer oil containment

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

RE: Old transformer oil containment

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.

RE: Old transformer oil containment

(OP)
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.

RE: Old transformer oil containment

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

RE: Old transformer oil containment

Quote (Not sure what the oil spill regulations are there.)


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

RE: Old transformer oil containment

(OP)
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.

RE: Old transformer oil containment

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

RE: Old transformer oil containment

(OP)
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.

RE: Old transformer oil containment

...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...ponder

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

-Dik

RE: Old transformer oil containment

(OP)
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?

RE: Old transformer oil containment

Quote (put more of an onus on the owner to maintain the system)


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

RE: Old transformer oil containment

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

RE: Old transformer oil containment

(OP)
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?

RE: Old transformer oil containment

Quote (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)


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

RE: Old transformer oil containment

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.

RE: Old transformer oil containment

Quote (doesn't pump if it senses oil)


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

RE: Old transformer oil containment

thanks...

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

-Dik

RE: Old transformer oil containment

I suggest talking to your mechanical engineer to explore the feasibility of employing an oily-water separator which is not rare in the powerplant.

RE: Old transformer oil containment

Quote (atrizzy)

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 interpret this as a simple manual valve that is normally off, after a rain event, a maintenance person would go to the site and open the valve to release excess water, then close the valve again. It would be up to the maintenance personnel to refrain from draining contaminated water/oil during this operation. This is a pretty standard design that I have seen implemented all over the US.

RE: Old transformer oil containment

(OP)
dauwerda, I meant a gravity oil-stop-valve. The type of passive valves that close in the presence of oil. Misspoke, apologize.
Here's what I mean: http://www.owstech.com/products/oil-stop-valves/
My understanding is that these aren't sensitive enough to stop small leaks.

RE: Old transformer oil containment

I do not know in which state you are located, but in our State such exposure would be answered thru an SPCC as long as the the quantity of oil on site requires it. Not knowing the quantity of oil in the transformer, I would approach the problem differently. I would determine the quantity of oil and figure out the possible direction of oil flow should there be a significant loss of oil in the event the casing ruptured. Then identify the closest storm drains and be prepared to stop the oil flow thru damming and plugging nearby storm drains. If the ground slopes is minor you could asphalt the area around the transformer so as to minimize seepage thru the ground. Clean up equipment in containers need to be with the area of the transformer. A berm around the transformer is also a viable method of containment. Responsible personnel need to be available to address an immediate response along with periodic inspections of the site. A standby clean up contractor should also be available. All of these measures along with several others not listed in my reply should be mentioned in the SPCC. I am not sure if the quantity of oil on site requires an SPCC but it would not hurt to have one nonetheless.

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