Hi Apologies for my appaling lack of technical terms! What I'm trying to check is about a Diesel tank (30,000 litres capacity), it has a suitable bund but an auditor has advised that the dispenser bit, i.e. the same as the bit you hold when you fill your car at a petrol station, should be within the bund enclosure. I was surprised because we thought the tank had been installed in accordance with the prevention of Pollution (Oil Storage) regs, but he seemed to think it wasn't. I've had a look at the PPG but wasn't sure what it meant. If anyone could clarify for me that would be great. Thanks in advance, Kay

I would argue that the nozzle need not be actually contained in the main tank bund but should certainly have an adequate catchment or bund of its own for smaller spills etc. This would apply if it were a pumped system with relevant check valves/controls so you can't simply drain the tank through the nozzle by accident. To contain the nozzle in the main bund could cause all kinds of additional problems and risks like people having to climb over bund walls to get to it. (obviously I don't know type / size of bunding etc.) If a gravity fed system/ manual control where the tank could be drained through the nozzle by accident or significant splillage caused, then I can see no way around having to contain the nozzle within the bund.

Kay If you folow this link http://www.defra.gov.uk/.../documents/oil_store.pdf It takes you to the guidance on the Oil Storage Regs. And covers the advice given by Bob and Alan John

NR, Para 32 of the guidance covers double skinned tanks and circumstances where a bund may not be required John

Kay Double skinned tanks still require the storage of the nozzle within the catchment zone of the bund/skin. I think it also best to remember that double skins only are effective if the puncture is more than half way up the tank. Below this level there will still be spillage into the environment. My advice is to ensure these type of tanks are stored in a bunded area when not required to be transported around site. Bob

there is also a raft of environmental law that applies so it can be a big issue to manage where a simple bund can solve most of the problems

Aaargh! I just typed and perfected a post only to find I'd been logged out! Anyway, I was going to say, thanks for all the posts and useful input. My problem is that we spent money bringing the tanks up to (what we thought was) the correct standard and now it sounds like we were mislead and yet more work is required. This means I will not have an easy ride to make it happen. Hence why I want to be doubley sure that what we have currently isn't good enough, and that whatever I suggest is the best possible and most cost effective solution. Regarding the (metal) red diesel double skinned tank, the tank is raised up ~1.5m on legs inside a skin which must be 200 - 300% capacity. Its nozzle has a drip tray that drains into this large outer skin. I gather that this is not adequate - correct? If so, then I guess we need to knock down the existing bund and make a new one big enough for both. But I'm still not clear on how the nozzles can be stored inside it and still be accessible for people to fill up. I would really like to show someone a picture and get some site specific advice, does anyone have any suggestions? Thanks very much, Kay

Kay, Not sure if anyone else has mentioned the Env Agency PPG series of publications is of great value. PPG2 deals with oil storage, covers the issue of double skin tanks and has a neat sketch. http://www.sepa.org.uk/pdf/ppg2a.pdf

If you have a positive displacement pump then your loss volume will be the fuel between pump outlet and nozzle, this should result in the provision of a catchment/bund area equal to 110-150% of this volume. However, from your description, you say that the nozzle catchemnt area is connected to the secondary containment? If that is the case then the secondary containment will be of no or little use as a release of primary containment into the secondary containment will result in a loss of containment from the nozzle catchment tray?????