Septic tank to water storage tank

[Howardws]

I have a 2M x 2M x 4M deep septic tank in my garden, unused for years. I live in the south east and I'm certain we are going to have water shortages in the future so I intend running the rain water from my garage and various other places into it. It was nearly full of rubble, old iron and soil that I have lifted out but I'm now down to soft wet sludge mixed with rubble. I can't find any local firm that is willing to suck the sludge out as none of them uses filters on the hoses and they obviously don't want rubble in their pipework, tanks and pumps. We're talking about 2M x 2m x 0.6M of rubbly sludge. Does anyone have any bright ideas please?

 

[jay679]

Just a warning, if you are actually getting into the tank to remove debris, then you really need full PPE and breathing apparatus - the sludge is likely to be human waste, so full of bacteria and giving off allsorts of unpleasant and lethal fumes.

Personally, i wouldn't go in it at all, is it possible to use something like a bucket on a rope as an improvised dredge to get most of it out without having to actually enter the tank?

 

[Howardws]

Thanks for the reply. A dredge won't work because there is too much rubble in the sludge, also the access is only about 0.5M x 0.5M so swinging something into the corners also won't be possible.

Thank you for your concern but I've already dug a few tons of rubble and dry 'sludge' out, plus quite a lot of wet sludge. I did it last year and haven't felt any ill effects yet! I stopped because the wet sludge was too awkward to handle and it won't dry out because the bottom of the tank is below the water table and it leaks. I did use a fan and trunking to ventilate the tank before I went in and kept ventilating it while working.

I had thought of pouring wet concrete into the sludge to make a floor and so lose a bit of the capacity but am unsure if this would work.

 

[Mursal]

Is the rubble suspended in it, or on the bottom? If its on the bottom, they will be able to suck the sludge out if you make a box for the end of their pipe. Something like a few blocks so that only the sludge can get to the bottom of the pipe. It will take a while but that cant be helped. If you add water will it help the thing separate?

I certainly wouldn't advise contact with the sludge wet or dry and certainly not in a confined space, but you know best

If you have enough capacity leave it as it is and get it working again as a septic tank, with a good water percolation pipe from the top (just below the inlet elbow) of the septic tank.

Or are you just going to use it for "clean water" storage? If so get a mini digger in

 

[ntb]

Storing water (that you are presumably going to use for something) in a well used septic tank? My mind is boggled.

 

[Howardws]

Using a mini digger through the small access would be a bit difficult I would have thought.

I've suggested to various contractors that a filter on the end of their pipe would stop the rubble entering their equipment but they don't want to know. It's not worth the bother I imagine, after all there isn't a great volume of sludge and charge is by the cubic metre.

I'm going to use the water on the garden. I'm on a meter so it will save a bit and anyway, when we next have a drought order I'll be able to keep my garden green.