Smelly Low Pressure Pipe System

[MasterPlumbersKeymaster]

We had to have a new septic system installed in April of last year, our block of 1 acre is mainly covered in bush so a low pressure pipe system was recommended. We have an aeration system – the main components of the system are a septic tank (aerobic unit), a pumping or dosing chamber (submersible effluent pump, high water alarm and supply manifold); and small diameter distribution laterals with small holes – in reality the laterals are 110mm diameter. We have less than 200mm of topsoil and a clay base in dense bush so the laterals were placed on top of the ground.

Almost immediately we started experiencing the most tremendous smells from the leach field. This by the way was placed down the hill from our house but a prevailing wind is blowing the smell back on to the house. We have had the company back quite a number of times. They have fixed a problem with the oscillating valve (this valve doses each of 4 lateral pipes in turn) which was not in fact oscillating. They have applied thick mulch over the laterals. Have moved the top lateral down to the bottom and finally (Today) have applied more mulch to the entire field.

The owner of the company admits the stench is unacceptable but thinks he has now solved the problem. I am less convinced as I can only see that when the mulch is saturated we will once again experience the odour. I think I am most concerned about the fact that at the times of dosing and for a while afterward we have raw effluent lying in puddles on the ground not able to soak away sufficiently because of the clay content of the soil. The smell is caused by these puddles (obviously) and is brought to the house by the unfortunate prevailing wind whipping up the gully.

So, what can we do?

[John Aldrich1Participant]

Carol, and New Zealand Septic System Professionals,

I have communicated with you regarding this problem, and have suggested that you post this message on the MasterPlumbers.com Bulletin Board so that perhaps a septic system consultant, installer, or regulator from New Zealand would respond to your problem, with knowledge of the unique characteristics of the approved systems in the Auckland area.

Carol, I hope that the thick layer of mulch solves the odor problem for you. However, I think that you still may have a problem with the potential of creating a public health threat by discharging the aeration system effluent directly to the surface of the land, without first disinfecting the effluent. A tablet chlorinator is the most common method used for small flow on-site systems.

You mentioned that the regulations there require that the dispersal field area be fenced, but I pointed out that fencing will only prevent people from accessing this area. Household pets, yours and your neighbors, will find a way to breach just about any fence. Cats, and dogs just love to roll in sewage, and sewage effluent. These critters can carry disease organisms that they pick up from rolling in the sewage back to the homes of their owners. Birds, insects, and other wild creatures also will have access to these puddles of effluent, and also act as disease vectors.

Good luck on solving your septic system problems, and hope that New Zealand professionals will respond to your inquiry. JWA

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