Soil properties and percolation
Soil properties and percolation
(OP)
Hi,
I am currently working on a project which involves a septic tank and will discharge to a raised mound soakaway system.
As part of the filter process the mound will be predominantly sand (percolation = 12 - 72 s/mm) however i also want to specify a 300mm thick layer of imported soil at the base of the mound due to the underlying soil conditions.
This soil layer will slow the absorption into the ground and i have indicative percolation properties of 2.4 - 288 s/mm. Unfortunately i have no idea what kind of soil has these properties and have no idea where to look so i thought i'd ask you guys.
Anyone got any suggestions?
I am currently working on a project which involves a septic tank and will discharge to a raised mound soakaway system.
As part of the filter process the mound will be predominantly sand (percolation = 12 - 72 s/mm) however i also want to specify a 300mm thick layer of imported soil at the base of the mound due to the underlying soil conditions.
This soil layer will slow the absorption into the ground and i have indicative percolation properties of 2.4 - 288 s/mm. Unfortunately i have no idea what kind of soil has these properties and have no idea where to look so i thought i'd ask you guys.
Anyone got any suggestions?





RE: Soil properties and percolation
I've seen some references in the past on perc rates and estimates of the coefficient of permeability. I'll try to look for it; perhaps others will have it handy. BUT, I am quite interested in the 'accuracy' of the rates you want to specify - and how you come up with them!
RE: Soil properties and percolation
However, these are only approximations. You could potentially set up a test program of different gradations and run lab perms on them.
Still, you won't really know until the soil is placed.
It is also difficult to specify a gradation if it's not readily available in the area where the work will be performed. You may want to compare some of the standard DOT gradations in your area to the chart I mentioned.
RE: Soil properties and percolation
Washington County, Oregon
Texture Permeability Percolation
(inch/hour) (minute/inch)
Sand > 6.0 < 10
Sandy loams
/porous silty loams/
silty clay loams 0.2 to 6.0 10-45
Clays, compact
/silt loams/silty
clay loams < 0.2 > 45
RE: Soil properties and percolation
Cheers
RE: Soil properties and percolation
RE: Soil properties and percolation
Close this thread i dont think it is going to get any where.
Thanks