Septic tank soakaway

[Burnerman]

No design there! I put mine in with a minimal fall so the effluent percolated through the perforated plastic pipe, into the ballast and then the land - this way no pits at the end were needed.
Again, I was very fortunate because the owner of the land wasn't interested in how long my outfalls were. The land was poor but absorbent enough....thinnish soil cover on top with sandstone blocks below, with a gentle downhill gradient.
John

 

[thelostcause]

I know of a soak a way that was built new in 1973 with the outlet pipe that ran down hill. Ever since then there has been a muddy patch in the field. I do not know what the "design" was. Its still in current use. This has made me very cynical about herring bone fields as the water will always run to the lowest end, so the rest of the field is wasted until the lowest bit blocks up.
Frank

That is my concern also Frank, doesn't seem the best design of soak away to me as getting it perfectly level isn't easy.

 

[chappers]

I know of a soak a way that was built new in 1973 with the outlet pipe that ran down hill. Ever since then there has been a muddy patch in the field. I do not know what the "design" was. Its still in current use. This has made me very cynical about herring bone fields as the water will always run to the lowest end, so the rest of the field is wasted until the lowest bit blocks up.
Frank

That's down to poor design.
On sloping sites the downhill runs should be in non perforated pipes leading to perforated pipes running across the grade of the slope, these should be closed at the ends. Either with separate effluent outlets for each level or separate holding tanks at each level to stop all the effluent just running to the bottom runs and to help distribute it sideways. but you are right there are often parts of the system that just never see any effluent particularly on systems with little use. Staggering the orientation of your perforated pipes or using porous clay pipes can help distribute effluent throughout the system
Even is correctly designed but built over an impervious layer, you can find that the effluent will just run down on top of the impervious layer and could appear anywhere that that layer comes close to the surface.
Pit soakaways have their own issues too they can silt up quickly around the outlet ,whilst the rest of the pit is still fine or fill up with liquid if not of sufficient capacity.

 

[Hugh Jaleak]

Septic tanks are like any other aspect of construction. properly designed and thought out systems will work trouble free for many years. Throw a tank in the ground, with a poorly designed soakaway and you'll have nothing but trouble. Been to tanks 100 years old that are still working well with an annual desludge, and also others in brand new homes that are backfilling as fast I could pump them out, as the soakaway was acting as a land drain in waterlogged soil.

The system simply couldn't cope with the volume of water being put into it, and a soakaway in clay soil with a high water table. Was never going to work.