Clay and pier hole drainage

[rich_t]

Hi,

I'm in the process of levelling an area of garden to place the telescope pier. Just to mark the spot where the pier hole would be I dug a small hole to mark the spot (about 8" square and 1 foot deep). After it rained on Saturday the hole filled with water and then late Sunday (after a day of sunshine) the water in the hole had only dropped about an inch. At the end of Monday the water had more or less dissappeared.

I guess I just wondered if there's anything I need to do for drainage of the final hole (like putting rubble/stones in the bottom first?) or does it just not matter? I was going to go for something like 3' deep x 2' square.

Thanks,

Rich.

[blinky]

I would not worry too much, its gona be filled with concrete anyway

[MikeD]

Yeah, my 3" x 3"X 3" was dug in clay, at the end of the day it an't gona be a hole for long.

Mike.

[ianporter13]

my 3" x 3"X 3" was dug in clay

you must have a small pier there Mike

I also dug a 3'x3'x3' hole into clay and just filled it in with rubble and concrete, and very solid it is too.

Ian

[MikeD]

my 3" x 3"X 3" was dug in clay

you must have a small pier there Mike

I also dug a 3'x3'x3' hole into clay and just filled it in with rubble and concrete, and very solid it is too.

Ian

yes it's for my EQ0.6.

[philsail1]

Mike,

I would echo the sentiments of other's advice with the water filled hole. All I would add is (and forgive me if I'm advising on something you are already aware of) when you come to pour the concrete in hole, try to put in a fairly stiff mix, and use a long piece of 2" x 2" wood to prod it around the pier. The stiffer the mix of concrete, the stronger it will be. (you need a 1:2:4 mix, and it needs to be stiff (or dry) enough to virtually stand up on its own when poured onto the ground).

Hope this helps.

Regards,

philsail1

[rich_t]

Thanks for the advice, much appreciated. I was thinking water may run between the concrete and soil and soften the clay around the concrete. Just need to get digging now!

[philsail1]

Mike,

Also, (if you haven't already done it!) try to dig the hole in a "dove tail" shape. It is the strongest shape for giving a firm unmoveable base for your pier. If you cannot dig in that shape, at least ensure that you "square off" the sides and bottom of the hole. ALso you must already know to ensure you have completely weather proofed the steel tube (or whatever) you are embedding in the concrete.

(click to enlarge)

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(click to enlarge)

Apologies if I'm telling you what you already know!

Regards,

philssail1

[SteveA]

Worth remembering that concrete will allow moisture through..so although its probably no big deal for a pier if you end up subsequently laying a slab onto which you put an observatory...it's worth considering laying a membrane first. Issues around excessive condensation within observatories are likely linked to laying concrete bases without including a membrane...

http://www.diydoctor.org.uk/projects/shedbase.htm

Steve

[rich_t]

Thanks again for the help and the pics, I've not dug any further so the dove tail shape should be possible.

Cheers,

Rich.