New Fosse Septique questions again

[Devon]

The strikers and the weather gods willing, I hope to install a Fosse Septique at my place in the Charente next month. I could do with a couple of pointers if anyone can help. It seems I should place a rock filter just after the tank outlet: can anyone tell me how the filter is installed and can they be bought off the shelf? Are the drainage pipes layed with a slight fall or level on the sand filter bed? How far below the finished ground level should  the drainage pipes be? Thank's for any info in advance [:)] 

[LesFlamands]

By rock filter I think you mean a 'prefiltre' which is usually a 500 litre chamber filled with 'Puzolene' lava rock in a basket which should be changed every 5 years or so. Sand filter pipes should or could have a very slight fall just to make sure they are not running back. Ideally all pipes should be 4-500 mm below the surface although depths are clearly specified for the sand filter. Spanc inspection is pretty basic - they usually check to see if you have the tank in level!

[pachapapa]

Practical simplicity...an FTE ( fosse toutes eaux) with préfiltre incorporated.

Usually contains pouzzolane but maybe plastic balls.

 

[Devon]

[quote user="pachapapa"]

Practical simplicity...an FTE ( fosse toutes eaux) with préfiltre incorporated.

Usually contains pouzzolane but maybe plastic balls.

 

[/quote]

 

Thank's pachapapa. I installed an FTE. The job was fairly straight forward. Pipe depths for the drainage bed was set by the plastic access manholes supplied by a local builders merchant. I made one error by not using solid pipe from the upper manhole along to the 5 drainage trenches (1m down for the central trench) This was easily sorted. A spanc inspection I tried to arrange by email did not materialise but after a visit was arranged over the phone by a French speaking friend, the inspector was very helpful and did not have a problem with me covering the drains as I took photographs of all stages of the work. I left the top of the tank uncovered so the inspector could check the tank was level. The only other requirement was a vent stack venting just below the Fosse exit.