Oil tank base build sanity check

johnnyboy08

Hi,

I'm looking for some advice around building a solid base for an oil tank.

The tank is 1.7m long and 1.1m diameter and the ground type under the topsoil is a very heavy marl.

My plan is to dig a 2.3m x 1.7m x 0.4m foundation, fill it with hardcore and then compact it. For the concrete I'm going to build a 2.3m x 1.7m x 0.1m form out of 4" x 2", level it on the hardcore and fill it with a 1:2:4 concrete mix.

Thing is, I've never even switched on a cement mixer (a pal of mine has an electric one though and is going to give me a hand). Is there anything I need to be wary of?

I haven't a clue of the curing process. Is that just a case of dampening the concrete when it's levelled in the 4" x 2" form?

delfagio

johnnyboy08 wrote:

The tank is 1.7m long and 1.1m diameter and the ground type under the topsoil is a very heavy marl.

Should be fine to put a base onto. Ita only holding up a tank, nothing too major really

johnnyboy08 wrote:

My plan is to dig a 2.3m x 1.7m x 0.4m foundation, fill it with hardcore and then compact it. For the concrete I'm going to build a 2.3m x 1.7m x 0.1m form out of 4" x 2", level it on the hardcore and fill it with a 1:2:4 concrete mix.

Similar to what I did when I done the base for my own oil tank. I dug out an area approximately 2.2m x 1.2m x 0.4m deep. I then put about 100mm of larger stone 4inch down and then put in about 200mm of Cl.804 stone and because I was building the house at the time I had a wacker plate on site and ran the wacker plate over a few times to compact. I then set up 4x2 timbers to form screed. I had concrete coming to site for another job I was doing so I ordered a little extra to do the base. After I poured concrete into formwork, I tamped it with the rake a few times to make sure the concrete was spread out everywhere and no voids were left. I then tamped it with timber screed to level off and used a bullnose float around the edges. Nice finish.

johnnyboy08 wrote:

Thing is, I've never even switched on a cement mixer (a pal of mine has an electric one though and is going to give me a hand). Is there anything I need to be wary of?

Pretty easy to set up and run this type of mixer, if possible have it set up beside the base your building so you could just tip mixer out and into the base, or you could just tip out concrete into a wheelbarrow if you can't get too close.

johnnyboy08 wrote:

I haven't a clue of the curing process. Is that just a case of dampening the concrete when it's levelled in the 4" x 2" form?

Don't level it perfectly level. I laid a slight fall on my base to stop any ponding of rainwater settling on it. I think from memory I laid a 20mm fall over the 2.2m length. Plus this meant I could have a slight fall on the oil tank itself.

K.Flyer

You also need to look at the installation instructions of the oil tank manufacturer to ensure that your base conforms to the requirements of the manufacturer and the guidelines of OFTEC.
Best practice would be to follow the Oftec Oil Storage Tank and Installation guides.

Here are OFTEC links to a Guide To Oil Tank Base Construction Pdf and Domestic Oil Storage Pdf which should help you to see what you need to have in place as a support for an oil tank.