When you live outside of a town area in Western Australia, then your house will need a Septic tank or similar sewerage treatment system. This simple yet effective system is designed to take in all the sewerage from a domestic house or commercial property. There are a few things that can go wrong with a Septic sewerage system to can cause it to fail. Some are fixed simply, while other things need the assistance of a licensed plumber.
A septic sewerage system is made up of a number of components. This includes:
A Leach drain also has a number of important parts too. The principle of the leach drain is to catch all the effluent from the liquids tank, spread it evenly across the leach drain field and then let it soak into the surrounding soil. Usually a domestic house has 2 leach drain beds anywhere from 9-15m long depending on the house size. A diverter valve is used on the inlet pipe so the effluent can be directed into on bank at a time. This allows the leach drains to dry out and break down the built up nutrients and recover, to increase their service life. Sometimes when the groundwater level is very shallow or the soil has really low percolating rates, then the local government will request that the leach drain is inverted or semi-inverted. This means that instead of being buried, the leach drain is installed on the surface or slightly dug in. Then a large amount of fast draining sandy soil is used to surround the leach drain and this light well drained soil helps evaporation and nutrient absorption. The parts of a leach drain are:
The drain is the main structure of the leach drain. It’s usually made of concrete sections 800mm deep 1m to 1.5m long and has an open bottom. Sometimes the leach drain is also constructed from mesh boxes made from reinforced plastic usually polyethylene, these can blocked easier than concrete but can be useful if the leach area is an unusual shape or is difficult to access. If there is a heavy non absorbing soil or a ground water level that is shallow, then there are wide and flat leach drain modules made from polyethylene that can be used too. Usually in modern times, the modules are covered by a geofabric which is a fluffy white synthetic matting. This matting is designed to let water leach out but it stops roots and sand from covering the holes on the sides and top and blocking the system.
Surrounding the leach drain modules is a vertical layer of bluemetal or similar large rock aggregate. This layer is usually 300mm to 600mm wide. It’s purpose is to hold the soil back from the outlets of the leach drains and let’s the effluent evenly percolate out across the leach bed so the nutrient loading is not concentrated anywhere.
One of the most important parts of the leach drain is the free part. The leach drain works by spreading the effluent over a large volume of soil. The native microbe population in the soil then set to work on the residual nutrients in the effluent and break them down and absorb them into the structure so the water can evaporate or leach away without causing pollution of the groundwater or your yard.
The most common problem that happens in a septic system is a blockage. Blockages can be in the following parts:
The other main problem that happens with a sewer is that it stops breaking down sewerage properly and starts to smell. This is usually due to a number of things:
The solution to this is to change the inflow to suit the septic, by sorting the leak or changing the chemicals used to more friendly options. The other thing to do is to add some septic enzymes (a brand we use is Bio-Pak) and then some nutrient. There are a few options for nutrients but the common ones are a tin or canned dog food or some sheep or cow manure. This releases nitrogen and amino acids into the tank and also puts a new population of good bacteria in which help digest all the bad things and get everything back in balance.
The other main thing that happens is that either one of the tanks or the leach drain can collapse. This can happen from old age, being made from poor quality materials or usually if someone drives a heavy vehicle or machine over it. While not really a breakdown of the septic, this can be very dangerous and needs to be repaired immediately so people (particularly children) aren’t hurt from falling in the hole or exposure to raw sewerage.
Any sewerage pipework in your house and out to the septic is plumbing work. Its has to be installed or repaired by a licensed plumber as it needs to be constructed properly to comply with the Plumbing standards. If there is a blockage in the sewer, a licensed plumber will also have the tools to either rod out or jet out the blockage and get the sewer clean and flowing again. Sometimes there might be root intrusion or actual damage to the pipework and so a section needs to be excavated up and repaired to make it work again.
In the solids tank, unless something is broken then the main thing to fix is removing the sludge build up. This needs to be done by a contractor with a suck truck and a controlled waste license to cart the sludge away. They have a special pump on their truck that can suck up sludge and they clean the tank completely out so that the sludge build up can begin again.
The liquid tank might sometimes get a build up of sludge in it that also needs to be sucked out when the solids tank is cleaned out, this is also good as it gives everything a clean start and gets the system to start working again properly. If the leach drains are inverted in any way or above the level of the liquids tank, then occasionally the sump pump will also fail. If this fails then the pump needs to be pulled out, disconnected by a licensed technician and then replaced with a new one. Small sump pumps are not worth fixing as they are only $300-$500 (for a good one) and you should get 5-10 years out of one. Its more inconvenient to get the pump in and out that for the sake of $100-200, you just replace it with a new one.
In the leach drain, most of the components are buried. So to repair the leach drain you need someone with a decent sized excavator and the skill to use it without destroying things too much. Usually the thing that goes wrong is a plug of roots and other debris on the outlets. To fix this, the soil and aggregate on the outsides of the leach drain need to be excavated and then all the blockages and roots cleaned away with a shovel or a pressure cleaner. Then new geofabric and aggregate can be reinstalled and the surrounding soil repacked around the leach drain. Depending on how saturated the soil is with effluent, sometimes this soil will need to be disposed of by a controlled waste license holder as this is classed as septage, or solid sewerage waste.
There are a number of properties in WA, particularly on the coastal plain that have a high groundwater level. There are also a lot of properties that have heavy clay soil and suffer from waterlogging in winter. These properties would generally be classified as unsuitable for a conventional septic system. Sometimes you can get away with an “inverted” leach drain, where the system is built into a mount of good soil sitting on the surface of the ground level. Gradually these days though Shire Councils are classifying properties as “ATU only” or “alternative systems only” and making the choice over the sewerage system needed much smaller.
In addition to normal septic systems, Oasis Plumbing and Southern’s Water technology have been installing Fujiclean ATU (Aerobic Treatment Unit) systems for around 3 years. These Japanese designed and Australian made systems allow you to build on a property where the soil or groundwater won’t allow you to treat sewerage with a septic system. While a bit more expensive than a normal septic system, they save you money in the long run and also don’t limit your house site selection to suit soil conditions.
I hope we have answered any questions you have. With any problems with Septic Systems, all repairs and excavation for them and the conversion or installation of an ATU system, then send us an email or give us a call on 0407 996 065.