The device is a cesspool of concrete rings
Mounting options cesspools of concrete rings
In fact, options like blind cesspool abound. Take the ring and bury them in any sort of depth, you can make the overflow wells. though it is called a septic tank. Below are a few design options.
Multiple cameras with overflow
separate sinks
Drains coming from the sanitary unit are divided separately from household waste and are in different wells. For the well with sewage from toilets prepared bacteria and lowered into the well. The bacteria consume all waste. It is important to the well with sewage from toilets did not get any chemicals as chemicals (detergents) kills bacteria, and cesspool (Via the link in detail about the pit) stops working. Using two cesspools you allow yourself to save on sanitation as sinks effectively processed and cesspools rarely accumulate.
Your cause, you can pit and set if the groundwater is not and you are sure that it does not spring flood. But I would recommend to install treatment plant, Tight and really cleaning drains.