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Septic Tank poor performance

Hi,

We have been assessing the performance of a septic for a village in Java, Indonesia. The tank, which serves about 75 houses with on average of 4 people per household, comprises a tank with approximate dimensions 2 x 9m followed by a leachate field with dimensions 3 x 9m. The tank is immediately adjacent to a small river and there is a constant discharge of clear foul smelling liquid into the river. We are unclear on how the discharge pipe is connected to the system, whether it is connected to the tank or is from a separate surface water system. We were unable to see inside the tank, but we have been told its not been emptied in 6 years.

We are looking for some advice on what could be potentially wrong with the system so we can advise the village leaders on their next steps. The discharge does not directly impact their community but they are keen to protect the environment and promote themselves as an eco-village.

We think the problem might be one, or a combination, of the below: - the septic tank is full of sludge - the pipes in the leachate field are blocked - the tanks and the leachate field are undersized - the ground conditions are unsuitable for the infiltration from the leachate field.

We have initially advised that the villagers that they should at the very least get the tank emptied.

Does anyone else have any thoughts or experience to draw on similar situations?

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7 Answers

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You need to check if the tanks are full by opening the covers for the septic tank and soak pit by opening the covers. If they are full, they may need to be desludged. you need to check where the effluent is coming from to decide where the problem is coming from. If it is from the septic tank , it could be that it is full, or leaking from the walls. If the soak pit is blocked but it may need to be cleaned by removing the stones and cleaning. This may be caused by poor soil soaking capacity especially in clay soil formations. In this case you need to verify the soil types.

I trust this will help resolve the problem.

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The fact that the discharge is clear is a good sign - then the septic tank is removing the solids. However the fact it is clear may mean it’s not coming from the tank or there is a sand filter polishing it to remove solids. I’m assuming the foul smell is “rotten eggs” - again a sign it is working.

It should be desludged as others have said, but check it has been properly built as sometimes septic tanks are constructed without a base. DO NOT ENTER THE TANK - IT’S VERY DANGEROUS.

As it is close to the river, a septic tank followed by a soak away may not be sufficient even if working properly. A constructed wetland can provide another treatment stage - a shallow basin filled with granular material planted with local wetland plants. Keeping the effluent level below the surface should help limit mosquito breeding.

Also check it is only receiving dirty wastewater. Rainwater can go straight to the environment so as not to overload the tank.

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Hi Tim, can you give a bit more detail on the water supply and sanitation system serving the 75 houses, so for instance do they have indoor water connections with flush toilets all connected to the septic tank. Best regards Tim Foster

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Collecting the nfomation suggsted by Tim Foster may help narrow the options and is supported. However ultimately you will almost certainly have to access the septic tanks, if not to identify problems then to effect remediation. Speculating is unlikely to beneficial, so adopting a systematic process of elimination with easiest tasks / access first would be my suggestion. Its a relatively simple calculation to calculate the expected accumulated volume in the tank (based on pit type and if water is used for flushing / anal cleansing, number of people per household, cubic volume of pit [plumb the depth if need be]) and this may give an idea if the tank is due for cleaning. I would suggest based on the limited information and a rough calculation with assumed pit depth and anal cleansing / flushing practice and , there is a good chance the pit is due for cleaning and this would in any event be a good starting point, and routine maintenance. It may produce initial mprovement provide access to the tank (if adequate access / cleaning hole). It is not clear from the post if it is discharging into the leachate field or directly to the river (latter is what seems suggested). The next step then seems to be to expose the connection of the pipes to ascertain connection to the tank and if the pipes are blocked - again possibly routine maintenace required. RedR manual and Helvetas latrines manual give guidance on infiltration rates for differing soils, however remember infiltration reduces over time. It is quite simple to do a rough infiltration field test and this may remove another variable as to soil suitability.

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It would be interesting to hear whether you were able to find a solution. Worth remembering that any water that comes out of the septic tank will be highly polluted so if it does not soak away properly, any surplus flow will inevitably be foul smelling. Septic tanks settle out solids but do not treat as such. Good luck.

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The fact that the discharge is clear is a good sign - then the septic tank is removing the solids. However the fact it is clear may mean it’s not coming from the tank or there is a sand filter polishing it to remove solids. I’m assuming the foul smell is “rotten eggs” - again a sign it is working.

It should be desludged as others have said, but check it has been properly built as sometimes septic tanks are constructed without a base. DO NOT ENTER THE TANK - IT’S VERY DANGEROUS.

As it is close to the river, a septic tank followed by a soak away may not be sufficient even if working properly. A constructed wetland can provide another treatment stage - a shallow basin filled with granular material planted with local wetland plants. Keeping the effluent level below the surface should help limit mosquito breeding.

Also check it is only receiving dirty wastewater. Rainwater can go straight to the environment so as not to overload the tank.

edit flag offensive delete publish link more
0

The fact that the discharge is clear is a good sign - then the septic tank is removing the solids. However the fact it is clear may mean it’s not coming from the tank or there is a sand filter polishing it to remove solids. I’m assuming the foul smell is “rotten eggs” - again a sign it is working.

It should be desludged as others have said, but check it has been properly built as sometimes septic tanks are constructed without a base. DO NOT ENTER THE TANK - IT’S VERY DANGEROUS.

As it is close to the river, a septic tank followed by a soak away may not be sufficient even if working properly. A constructed wetland can provide another treatment stage - a shallow basin filled with granular material planted with local wetland plants. Keeping the effluent level below the surface should help limit mosquito breeding.

Also check it is only receiving dirty wastewater. Rainwater can go straight to the environment so as not to overload the tank.

edit flag offensive delete publish link more
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