Old heating oil tank

[mutleybones]

With lots of hot soapy water and a power-washer, would such a tank ever come clean / smell-free enough to use for rainwater. The tank is steel and hold 4000 litres and is being offered nearby to anyone who can take it away. The project I have in mind is to capture the rain off a barn roof to keep a small pond for ducklings refreshed and topped-up through the summer.

Obviously, I don't want an oil-slick / sheen on the water, especially as the ducklings are for eating (bless 'em).

Steve.

[camillitech]

Morning Mutley,

dunno about steel but I have done it with many plastic oil tanks. Balmoral made a huge batch from inferior Swiss plastic and after about 5 years they started to spilt. i have about half a dozen of these and have used them for various projects after cleaning and power washing. With your steel tank a good cleaning then sealing the inside with some kind of non porous paint may be the answer. You would probably need to do that anyway as being an oil tank it's unlikely to be coated on the inside.

Good luck, Paul

[MR GUS]

Don't see why not, however do use a de-greasant in your cleansing & make the top piece a lid, perhaps if proper cleaning & renovation is too much in terms of time, you could prep it & line it out? then use it..

[dhaslam]

I am planning a pond for wildlife to be fed from roof water,  but I was thinking of allowing the level to change. I intend to put sand over the liner to protect it from the sun.    The pond will also serve as a water store for a slightly smaller pond near the house.     It is quite hard to store enough water in a reserve tank to make up for  dry spells unless the pond is very small.   

[Baz]

Birds seem to accept contaminated water, but I bet you would have a hard time cleaning it enough for a horse to drink willingly.

[mespilus]

A drum of an industrial detergent,
like traffic film remover as used in
(hand) car washes is probably your best bet,
although,
watch out for the alkalinity,
as most contain a good dollop of caustic soda.

Quite what you will do with the effluent,
water/heating oil/detergent emulsion
and lumps of 'crud' will need some consideration.

[mutleybones]

I'm rapidly coming round to sticking to my original idea of 3x IBCs stacked up, with the bottom one used as a sand filter and the top two connected together and used as a header. Add to that a solar-powered submersible pump to recirc the pond water through the sand filter and a way of back-washing the duck poo out of the sand.

Time to scrounge some IBCs. The thought of the effluent from the cleaning of the other tank was enough for me.

On a separate subject, but involves the use of rainwater, I was also thinking of incorporating some trays (2x1m) into the design of the duck-house roof to grow water-cress with the run-off going to the pond, bugs and all. Anyone done anything similar? And would welcome suggestions for the trays - my brother is in the RAF and they have 2x1m drip-trays under the planes. If they ever decide that they are going to close Lossiemouth I'll ask him to bagsie them.

Steve

[mespilus]

If you have the space, to not need to stack the 3, (or 4?), ibcs
you could always run them as an upflow weir.

Plumb together the 2 inch outlets through a filter
and pop the duck poo in the compost?

[dhaslam]

The 2X1 trays would be  good for filtering, you can get  filter media in sets of three  and you would need four trays.   I am planning to use water cress in a stream running back from the filters to the pond.   

www.koi-zone.co.uk/Filter-Foam-Sets-Pond-Filter-Media-sc-644.html     

[Baz]

Doesn't watercress need clean fresh water not pooy run off. Gosh, I still associate watercress with the typhoid problem in the early sixties.

Perhaps someone  can use the tank as a heat store. 4000 litres would hold about 200KWh.

[dhaslam]

Watercress is commonly used to remove nitrates from moderately contaminated water.  For eating it  would be better to grow it separately in clean water.

The other cleaning agent to use is  straw.   It acts as a  home for bacteria that break down  ammonia to nitrates.

[mutleybones]

Thanks for all the response.

The water-cress was going to be fed directly from the rainwater with the run-off going to the ducks, I am intending to cut the bottom tank down to make the filter bed. The other two being there to catch the rainfall and to function as a header tank to feed the veg garden irrigation.

We have another rainwater cistern underground (30,000 litres) that we used last year to great effect, in fact we ran it dry from full. The pump for that is a 1kw jobbie with a 100l reservoir vessel, and can feed the veg garden 100m away uphill no problem, but, in the absence of PV I'm now thinking about having a header tank and using the 1kw pump overnight to fill it as our electric consumption went up 20% over the summer.

The KoiZone link has proved to be a major distraction, so many things to choose — so much for the little winter project. 

Steve.

[Tombo]

I have cleaned out a few old steel diesel and kerosene tanks for  drinking water storage for livestock.
The method I have used successfully is as follows:
Cut a man hole towards one corner of the top.  Bracing crosses the middle of of the tanks I have opened so a corner hole makes it easier to get in.
Get in and shovel in to buckets the sludge and rust.
Fill the bottom of the tank with scrunched up balls of news paper, get out of the tank and set fire to the paper. This will burn most of the remaining oil and cause any loose rust to drop off. I have blown compressed air in via a drain plug get the fire hotter but its not always necessary on a nice warm day.
Once its cooled down pressure wash off the insides.
I have often considered painting the inside of a freshly cleaned tank with red oxide however I have had 10 years use out of previously scrapped tanks without painting them and considering how unpleasant it is inside a tank, I'm not sure it's worth while.  If you do paint it be careful of the fumes, you will be in the tank for far longer than it takes to clean the tank out.
Burning might sound dramatic but it works well and you produce far less oil contaminated water than washing alone.

[Philip R]

A few years ago, I had some white metal bearings re-metalled.

The manager of the works, whom was visiting me on site, told me that molten babbitt metal does not take to steel or bronze that has been immersed in oil, unless heat treated to burn out the oil absorbed into the surface.  This backs up Tombos thought about lighting a fire to burn off/ out the residues.

Detergent washing not enough, otherwise it will take years for oil residues to wash away in molecular quantities. 

PhilipR

[mutleybones]

I had thought originally about burning and then remembered a tale of someone at Land Rover (ex-employer) cutting the top off a lub oil drum with a torch. The drum exploded and wrapped itself around him, he died on the spot. Recommendation* after that was that all drums to be cut/burnt were first brimmed with water.
This put me right off having a fire in it.

Since, my earlier posts, I've been on a keeping my eyes peeled and saw 3 black IBCs at the rear of a local goat shed in what looked like the 'junk corner', I'm presuming they previously contained disinfectant/teat cleanser. Will enquire.

* not sure if this was H&S law, procedure or word of mouth.