With all these recent rains resulting in water logged land, some may be having problems with waste water Soakaways.
I hope I am not speaking too soon, but I have three soakaways in my garden, none have given any trouble this year or any trouble since they were put in.
My main soakaway is from my septic tank, which is a large 3 chamber system, which then feeds into a deep underground soakaway, which is about 4 feet wide, 30 - 40 feet long on two sides and about 8 - 9 feet deep. . . . In its bottom there are large stones, then smaller stones and even smaller, then covered with several layers of plastic sheeting and finally with about 3 - 4 feet or regular garden soil. ... There is no indication on the surface lawn and plants where that soakaway is.
Then I have a soakaway for the washing machine, this starts with an outside, open 3" drain, covered with gauss, feeding into three 2" branches about 4 ft deep, in sand, covered with plastic and 3 ft of ordinary garden soil.. . . There is a section of those 2" pipes, that has an open ended 6" pipe section, to act as a large rapid water storage, from the washing machine.
Finally, I have a garden or is that house roof, drainage, consisting of two 2" perforated pipes, buried in a gravel trench, about 12" deep, then covered with regular soil. . .. This now keeps the whole garden free of rain water.
All these systems have been working well during these exceptional rains.
A point of interest.
Underground water flows better through moist, damp soil, not dry soil.
So the outflow of waste water from a house, depends on the general soil in the area ability to allow water to move, clay soils are poor. .. . . It therefore also depends on the the area of contact between your soakaway and the natural ground.
So soakaways have to be large enough and or deep enough to be able to maintain more outflow of waste water than the water input from the house.
I have a closed system for grey and black water,that works great.
450 gal tank I built.1/2 way up from the bottom(below the sludge) 2" pipe connects to the blue barrel at its center and it outlets at the top into a second barrel with a 2" outlet to the transpiration pit.
The bottom of the8'x30' pit is clay that slopes down5" front to back.Septic water runs down in 8" of river rock,then a sealing membrane,then sand to form a mound,then topsoil about4"" that forms the mound ,to shed rainwater.
Various varieties of banana are planted on the edge of the plastic on the long axis and their roots soak up all the household water and provide delicious,bacteria safe,fruit.