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Fosse Pump Question SVP


UlsterRugby1999

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Morning all. We have a renovation project underway at the moment which requires a 4m³ tank and a 6x5m sand filter which requires a pump. I have asked my local materials supplier for a devis for the materials and he has included a pump and a reservoir for the pump at a cost of nearly 1100€.

Do I need to use this costly pump or could I simply buy a much cheaper submersible pump instead? If the answer is YES, what sort of reservoir do I need and do you have any idea what its called (in case I'm calling it the wrong name) and where to get one?

Cheers folks - Paul

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I presume the sand filter bed is drained and the pump will be used to elevate the "clean effluent" to a higher elevation for disposal by gravity. If that is the case the "water" will be clean without suspended particles and an expensive pump may not be necessary. The reservoir accumulates the water so that it is pumped in batches intermittently preventing the pump bashing it's innards out on snore. If it was my installation I would go for a good quality heavy duty polypropelene plasti dustbin and sous-sol dirty water pump with a rubber impeller and mercury floats. I would anticipate a cost of €70-€80 not including excavation and frost insulation. 

The pump will be called a "pompe de relevage" and the reservoir a " bac"; similar in concept to a "bac dégraisseur"

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[quote user="pachapapa"]I presume the sand filter bed is drained and the pump will be used to elevate the "clean effluent" to a higher elevation for disposal by gravity.  [/quote]

Yes pachapapa - it will be as you describe.

[quote] If that is the case the "water" will be clean without suspended particles and an expensive pump may not be necessary. The reservoir accumulates the water so that it is pumped in batches intermittently preventing the pump bashing it's innards out on snore. If it was my installation I would go for a good quality heavy duty polypropelene plasti dustbin and sous-sol dirty water pump with a rubber impeller and mercury floats. I would anticipate a cost of €70-€80 not including excavation and frost insulation.[/quote]

Which is what I thought and hoped would be the response. Many thanks for your input. Cheers.

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Many will use two pumps in installation in  case of breakdown of one pump.

I am busy at mo' and must pop into Parthenay but to be going on with a snippet from a good SPANC forum; even the french get super high devis.[:D] As I understand it there is no regulation as to how you elevate the water; perhaps a hamster on a wheel will be pleasing to the "tree huggers".[:)]

http://www.spanc29.net/forum/index.php?topic=1066.msg7850#msg7850

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  • 2 weeks later...

[quote user="La Guerriere"]If you're passing through UK try Machine Mart, they do a good line in cheap submersible pumps[/quote]

Cheers for that but I doubt I'll be in the UK for a long while. The bin type unit is more my concern. Given that the base of the collecteur will be circa 1.5/1.8m down its the logistics of doing this I dont quite understand.

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What sort of elevation does the "water" have to be lifted from the collector of sand filter to wherever you intend to pump it?

The need to pump from a sand filter is very rare as most properties in the country have some sort of natural drainage. In the rare case of pumping being required the only practical alternative for any contractor is to supply a proprietary "station de relevage with pump and cuve plus electrics in a complete kit. Such installations are widely used for the lifting of "eaux usées" to a collective sewer. They come in different sizes from individual dwellings to blocks of flats. They are capable of dealing with most everything from sanitary towels to dead hamsters. I consider Flygt to be the best manufacturers of this type of dirty water pump and their catalogue and installation instructions give an idea of what to aim for when designing your own installation. The PDF file below gives a general idea of the Flygt Micro Station de Relevage.http://www.flygt.fr/1823322.pdf

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If the Fosse Septique is correctly installed and maintained, then the intermediate pumping station only needs to lift clean (but still marginally septic) water to the discharge field.

The recent installation  at a close friend's house has to overcome precisely this problem: the house and thus fosse are well beneath the level of the discharge bed.

So his system has a small square elongated (Deeper than wide) grey plastic tank with an automatic pump enabled by float switch. And a Tampon de Visité.

If the system is discharging solid matter such as sanitary towels, dead wildlife and etc, then the field would soon be blocked!

The only time solid matter can be discharged from the fosse is when it urgently needs emptying and maintenance, because it is full of solid matter to the point where this is flooding over to the level of the discharge pipe outlet: and the anaerobic bio-degredation process has stalled.

Simple enough anyway to install a rodding point and tampon de visité somewhere between the tank and the lift pump sump: and the manchon could include a - removable -  gauze filter to prevent damage to the pump.

 

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GS your buddy's pump position is between the pretreatment and treatment stage whilst the OP's is AFTER the treatment stage viz: on exit from a vertical drained sand bed filter; at this stage the "water" would be perfectly cleaned with no suspended matter. The fact that your friend has his pump between the fosse septique and the filter bed indicates that there is a 90% probability that his filter bed is a vertical non drained sand filter bed; this type of installation is used on ground allowing a slow percolation rate into the bedrock such that aerobic effects will continue to occur. Such an installation can not be used  where the bedroock is impermeable or conversely where the permeability is so high that pollution of aquifers might result. Undrained vertical sand bed filters are frquently installed in La Vienne. Nevertheless your friend's installation emphasises that there is no need to install expensive pumping arrangements intended for pumping raw sewage; the OP will have even purer water so less of a problem.[:)] The OP will have a slight problem of elevation as he seems keen to have the inlet to his pumping system at the same height as the "exutoire" from his filter bed; this will perforce be between 1.20-1.50 metres below ground level. There is of course no reason why the pump facility is located immediately adjacent to the collection point of the filter bed and frankly I would have thought that an additional 100 mm pipe run could convey the outflow to a more favourable position for the installation of the pump set-up.
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Cheers guys for all the input. Pachapapa you have it about right. The technician from SIVEER has asked for a collecteur and pump as the fosse outlet will be approximately 1 metre below the land drainage line that it will connect to that will then take the water to the nearest fossé. The pump is to be positioned immediately after the regard de bouclage.

 

The issue now is sourcing the collector/collecteur as the pumps seem to be readily available.

 

Given that the land drainage is circa 600mm below the ground level the collector will need to be quite a deep unit and this is where I need your help. Where would I expect to find one of these type of units. The local supplier, as I’ve said, is quoting nearly 1100 € for pump and collector.

 

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It's much simpler, pach.

The house is well below the level of the filter bed (Which is a simple horizontal bed): and thus it cannot rely on gravity as it must feed treated final water upwards: thus the FS exhausts into a small sump and automatic pump which then on demand shoves the clear water uphill into the filter bed.

I will suffer precisely the same problem when in the not too distant future I will be compelled (Loft conversion: two more beds and living room) to install a new FS system, as the front of the land (Where the house is built) is well below the level of the most appropriate site of the discharge field/filter bed.

All good fun.

And just to think, by order of the deputies, all la belle France was going to be served by main sewers by 2005!

[:)]

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The pump is to be positioned immediately after the regard de bouclage..... What is depth to bottom of filter bed?  The collector is conventionally a plastic cuve containing the pump with vertical extension pieces that are added to get extra depth. In the context of the filter bed being installed have you considered getting the terrassier to dig out an excavation extending from the "regard de bouclage" position to accomodate the installation of the pump and cuve? The depth sufficiently below the base of the filter bed for drainage from the bouclage and of capacity to allow batch pumping. If it was me I would be looking at one of these "récuperateurs de l'eau" that one sees in the garden sections of the Bricos, there are some square section ones that must be a good 2 metres in height. The square ones have ribbed designs making them more robust. In any event when you get it in the hole dug by the terrassier and connected to the 100 mm outlet from the bouclage you can backfill around it with a lean sand cement mix, say 12:1 to make the excavation stable from any ground pressure. The sand required of course delivered at same time as the graded sand for the filter bed.
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pachapapa - I'll be doing this myself as its our wee project. The sand filter must be a minimum of 1.5m from the base to the top and the regard de collecte comes in line immediately after the regard de bouclage. I had assumed that the regard de collecte would be where the pump would also be positioned. If this is the case, then it would save me having to excavate deeper and get the water pumped up and into the land drains. Have I got this right?

I see what you mean about the water collectors. This sounds like an excellent and cost effective idea. To make the connections I guess I simply cut into the vat and PVC weld the pipeworks in place or are there clever connectors.

Thanks for your input here.

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I know folk in the vienne with a siveer approved pumped set-up. Its FTE then pump chamber 40mm PE pipe to the regard, epandage and another regard. Try frans bonhomme or pum plastique for the pump chamber.

They had a horrible stench in their house. I traced it to the gaine feeding the pump. The gases were going up it and venting in their GTL. Nice.

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