mound system washing away...

[jduncan]

I am new to septic systems - so if this seems silly I apologize in advance. We our in Central Texas - very little soil and solid rock at about 6 inches. We have a raised drain field - I believe it is called a mound system. Anyway, the soil continues to wash away exposing the pipes at the edges. I have hauled in more dirt, only to watch it erode away as well. Would it be ok to install a retaining wall to keep the mound from washing away? It seems to be washing away only on one end, can I place a wall at one end or do I need to go all the way around it? Any other advice would be helpful. Thanks!

[suemarkp]

Is there grass planted on this mound? That should help hold it together. I also wonder if your pump is setup right -- may be pumping water too fast into the mound, or one pipe getting too large a share of the water.

I'm not sure what effect the wall would have on the mound, good or bad. You can probably make the mound larger without ill effect. Just make sure the soil is the correct type which has the correct perk rate -- sand would be bad (too fast) as would clay (too slow).

[case580]

Normally mounds only have about 6 inches of drain rock over the pipes (1 to 2 inch diameter pvc) with filter cloth over the rock and then covered with a foot of soil a mound system area pretty much allows for evaporation area for the effleuent and treatment of the effleuent as it passes through the mound system. The eroding away of soil which I assume is caused by the flow of effluent rather by rainfall is not allowing the treatment of effluent and is causing a potential health hazard

Is the Dirt you are hauling in the same as what was originally installed on the mound ????

If you build a wall where is the effluent going to go if there is rock only 6 inches down ?


Speak to who installed system or the inspector who ok'd the installation if current

Sounds like the dispersion field manifold ( a series of pipes) may have a pipe broken or a coupling that was not glued. You may have a blocked line or lines

Do you have the plans for the system ? Does the county or city? If you can look at the plans it will show the design of the dispersion field manifold an may help you on fixing the problem.

Sometimes contractors don't follow the plans to a T.

http://www.soils.wisc.edu/sswmp/SSWMP_15.24.pdf

Hope this help a bit

[scuba_dave]

The original poster has not been back online since his 1st post

[wastetech]

Mounds tend to be washed away when too much effluent is pumped in too fast. The liquid rushes to the lowest drain and punches a hole in the mound. there are several things you can do:-

Alter the floats in the pump chamber so that less is pumped/cycle
install a pump which pumps at a lower pressure
check the distribution box to make sure that it has not sunk or gone out of line, letting more effluent flow down one drain
excavate the mound where the problem is and lift the end of the pipe so that it is no longer the lowest point


The comment re. sowing grass on the mound is also very relevant. Also, look at http://www.wte-ltd.co.uk as it shows how a septic tank mound should be constructed.