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How to build an infiltration & soil bed
Installation instructions for infiltration & soil beds
Read more about our infiltration beds & soil beds at this link
Infiltration is by far the most common form of treatment technology in Sweden. Soil beds are used where the ground is too dense to be infiltrated. Dense soil beds are used when no water can or must be discharged where the bed is placed and in cases where all water must be led through a phosphorus trap after treatment in the bed.
Building an infiltration or soil bed does not look so difficult, but unfortunately there are an incredible number of installations of infiltration beds in Sweden that work very poorly.
There are many different opportunities to make mistakes, even experienced excavator operators make mistakes many times when they have not read how to do.
It is you who will suffer in the first place if the function is deficient.
It is therefore wise to ensure that the installation of your sewerage system is done correctly, that the components have the right function and that the right materials are used.
By law, the contractor has a 10-year functional guarantee on the installation, and unfortunately there are many products sold on the market that do not work.
Be careful when choosing a product and contractor, then the system will work well for many years.
As the property owner, you are always responsible for the function. It does not matter that it is approved by the environmental office the week before, if the treatment does not work.
Every week we get questions about spare parts that don’t exist for a supplier that no longer exists, choose products from well-known manufacturers that have been on the market for a long time and are financially sound.
When designing an individual sewerage system, the following must be taken into account:
– Household size.
– Soil conditions, terrain and soil types
– Groundwater conditions
– Topography and slope conditions
– Proximity to water source
– Depth to bedrock
– Topography of the bedrock
– Proximity to a lake or watercourse
– Climate and soil frost conditions
– Local regulations
– Proximity to road
– Distance to property boundaries (neighbors)
– Ventilation in the house
– Distance for the sludge truck
– Drinking water purification technology
– Energy boreholes nearby
– Size of bathtub
– Water quality of drinking water
The municipality’s environmental and health protection office will come after the application and inspect the intended site for the sewage plant.
Often, test excavation is required for so-called sieve analysis or percolation test, i.e. measurement of the size distribution of soil particles.
The analysis is also done to study groundwater conditions, which determines the ability of the wastewater to penetrate into surrounding soil layers.
The distance between the infiltration level and the groundwater surface shall be at least 1 m, except for short periods (maximum 2 months in a year). The distance between the infiltration level and the groundwater surface shall never be less than 0,5 m.
Sand and macadam for infiltration
The quality of the sand and macadam materials used should follow the instructions in the Swedish Environmental Protection Agency’s publication “Small sewage plants”. The environmental protection office in the municipalities often has good knowledge of where you can obtain the right materials for your infiltration or soil bed. The macadam must be washed to avoid clogging of pipes and bed. Otherwise, the lifetime of the system may be shortened. The material separating the layers of the bed should be finer gravel, such as garden shingle. Above the bed, non-woven fabric is used to separate the backfill material (humus) from the macadam.
General advice
Sewage pipes, sludge separators and distribution wells should be filled with sand or fine gravel. Pack carefully. The slope must be carefully measured with a spirit level.
The slope of the spreader pipes in particular must be exactly as specified. Ensure that surface water is drained away above the infiltration and soil bed.
Sludge separators must be emptied at least once a year. The spreader pipe and any collection pipe must be terminated above ground level with ventilation hoods.
Please note! House drains shall be vented on the roof of the house above the ridge. Vacuum valves shall not be used.
Sludge separator
The function of the sludge separator is to make the flow as slow as possible, so that the coarsest particles sink to the bottom of each chamber and grease and oil rise to the surface. The water is then discharged via a distribution well for treatment in the infiltration bed or in the soil bed.
Location on the site
The sludge separator must be placed so that it can be easily accessed by sludge suction vehicles, normally a maximum of 10 meters. Otherwise, a sludge suction pipe may be installed.
The sludge separator or bed must not be placed so that it is passed by vehicles that cause increased ground pressure.
To reduce the risk of clogging, take advantage of the topography so that the soil pipes from the house have a smooth fall, avoid unnecessary bends.
We recommend that a cleanout be installed on the sewer line just outside the house foundation and every 20-30 meters. This facilitates flushing of the line in the event of a blockage.
The infiltration or soil bed for a normal household takes up an area of about 16-30 m2. If biomodules are used, the area will be smaller.
The total area for a complete plant with sludge separator, infiltration bed and wells etc. is easily 50-100 m2
Keep in mind that the life span of the bed is about 15 years, when choosing the location.
Infiltration or ground bed – what should I have?
Infiltration bed
Is the most common type of post-treatment stage. The ability of the soil to receive the wastewater determines whether such a facility can be used.
In the infiltration bed, treatment takes place at the bottom of the macadam layer, the sand and in the surrounding soil layers.
An infiltration or soil bed facility can be constructed as a uniform field, in which case the distance between pipes is 1.5 m. Alternatively, they can be constructed as separate trenches with a pipe spacing of approximately 2 m.
Soil bed
In cases where the soil’s absorption capacity is poor,
for example due to high groundwater, proximity to mountains or excessively dense soil layers such as clay, the water must instead be treated in a soil bed and then discharged into the environment. The soil bed consists of a sand bed where the wastewater is filtered and treated and then drained away and led away.
Sometimes you have to make the soil bed tight with a large rubber sheet around all sides except the top.
How to install infiltration and soil bed systems
Described from the top down, but of course the installation is built from the bottom up.
1. Spreading layer
The spreading layer is an approximately 30-40 cm thick washed macadam layer with a grain size of 12-24 or 16-32 mm.
The bottom of the trench should be level and smooth, but not compacted no trampling and no vehicles.
The trench may be common to several spreader pipes or provided with a separate trench for each pipe. The separate trenches may be directed in different directions from the distribution well.
2. Spreader pipes
The bottom of the trench is leveled to form a base for the macadam layer.
The spreader pipes are placed in the macadam layer (gray edge upwards) so that the fall of the pipes is 0.5-1 cm/m and so that at least 30 cm of macadam is under the pipes at the end. At least 5 cm of macadam (12-24 or 16-32 mm) shall cover the pipes. The total thickness of the macadam layer is 30-40 cm.
Bends are installed at the outlet ends of the pipes, and aeration pipes are connected to them, which should reach above the snow cover in winter.
The distance between the spreader pipes in the same direction in separate strings shall be at least 2 m. The distance between the pipes in a common shaft shall be at least 1.5 m. The maximum length of each individual spreader pipe is 15 m. The pipes are extended with joint sleeves.
Finally, lay the fleece on the macadam and backfill the shaft.
3. Filtration layer
The filtration sand is placed under the spreading layer. The phosphorus is bound to the sand and the organic substances are broken down in the bio layer. The filtration layer is made of sand with a grain size of 0-8 mm. The thickness of the layer is about 85 cm. On top of the filtration layer there is a distribution layer, with spreader pipes, fiber cloth and filling soil.
4. Collection layer (only for soil beds)
The collection layer is the bottom layer of the soil bed and its task is to collect the treated wastewater, which is then led in collection pipes to the outlet well.
The collection layer uses collection gravel with a grain size of 8-16 mm. The thickness of the collection layer is approximately 30 cm.
5. collecting pipes
Collecting pipes are drainage pipes with holes all around through which the treated water is led away. The collection pipes are laid in the collection layer with a slope of 0.5-1.0 cm/m.
At the ends of the collection pipes, bends for aeration pipes are placed well above the ground surface. Aeration hoods are fitted to the aeration pipes
6. Outlet well (only in case of soil bed)
The collection pipes are led to an outlet well which also serves as a sampling well.
Level an outlet well bed to the correct level. Place the outlet well vertically and fill sand around the well.
7. Outlet pipe
The treated water is led from the collection well through an outlet pipe
(110 mm) to a suitable place in the terrain, e.g. an open ditch.
If the level differences on the plot are not sufficient for self-fall, the treated water must be pumped to the outlet point.
The outlet of the discharge pipe should be fitted with a stone coffin to protect against ice plugs and prevent small animals such as rodents from entering the system.
8. Sealed soil bed
A sealed soil bed is constructed by laying a rubber sheet around the entire shaft for the soil bed. Rubber sheets prevent wastewater from entering the groundwater.
A rubber sheet measuring approximately 15 x 7.5 m is laid out along the bottom of the trench.
The rubber sheet is also laid over the ends of the trench. Make sure that the rubber sheet is not damaged when it is laid out. The edge must not be turned in over the soil bed, as this prevents the air supply to the microorganisms
in the soil.
9. Pumping
It is very common to have to pump the wastewater. It is easier to pump the water after the sludge separator and this can be done in two ways, with a pump integrated into the sludge separator or in a separate pump well.
It can be good to have a level alarm that warns if the pump is not working properly.
Usually 32-40 mm PEM hose is used from the pump to the distribution well or directly into the spreader pipe.
If possible, install a straight 110 mm pipe with self-draining 1-2 meters before the distribution well. This will dampen the incoming flow.
The pump should be fitted with a non-return valve to prevent water from flowing backwards when the pump is not in operation. Many starts and stops on a pump are what shorten the ‘life’ of the pump.
If the pressure pipe cannot be installed frost-free, frost protection type: insulation and often heating cable must be installed.
Please note! The pump well shall be vented between the distribution well and the pump well
Self-inspection
Sludge separator
When emptying sludge, the chambers must be emptied in order; first, second and last third chamber. This is to avoid any sludge escaping between
the chambers. After emptying, the sludge separator must be filled with water in reverse order.
At least once a year, preferably in conjunction with sludge emptying, it is a good idea to inspect the sludge separator visually. Check the lid and the lock, but also, if possible, inside the separator, for any fouling. Rinse if necessary.
Sludge stop filter is a good accessory that is inserted in the outlet T-pipe of the sludge separator that prevents sludge from going out and clogging the bed.
Distribution well
Once a year the distribution well should be inspected.
If there is a lot of sludge in the well, it means that there is something wrong with the system.
Check the lid and lock. Fouling can form in the distribution well. If there is little growth, it can be flushed away.
If there are large amounts, you should try to collect most of it and then flush because of the risk of clogging. This is an indication that the distribution well needs to be inspected at more frequent intervals.
Pump and pump well
The pump should be inspected and maintained according to the pump manufacturer’s instructions. Check the function of the non-return valve to avoid “backflow” in the system.
On the pump well, it is important to check the cover, locking and connections between the pump and the PEM pipe.
If in doubt about the function/condition of the electrical connection, contact an electrician.
Infiltration/collection pipes
These pipes can be inspected through the air pipes. Insert a stick/rod into the pipes to check that there is no water in the pipes. If there is water in the pipes, the bed is not working properly.
The high water may be due to temporary or constant change in groundwater conditions. This must be monitored until the water subsides. If there is still water in the pipe at normal low water, the installation must be drained or rebuilt.
Check that the air pipes and ventilation hoods are not blocked.
Outlet well
Check that the lid and lock are intact.
Is the water in this well colored and smelly?
Then your soil bed is not working properly and should be fixed.
Level alarm
The sensor for the alarm is lifted and flushed clean. Test the function of the alarm.
Service diary
Do not forget to note sludge emptying and ongoing maintenance in the service diary.
This facilitates troubleshooting and fulfills the requirements for self-monitoring according to general advice.
0 €
Installation instructions for infiltration & soil beds
Read more about our infiltration beds & soil beds at this link
Infiltration is by far the most common form of treatment technology in Sweden. Soil beds are used where the ground is too dense to be infiltrated. Dense soil beds are used when no water can or must be discharged where the bed is placed and in cases where all water must be led through a phosphorus trap after treatment in the bed.
Building an infiltration or soil bed does not look so difficult, but unfortunately there are an incredible number of installations of infiltration beds in Sweden that work very poorly.
There are many different opportunities to make mistakes, even experienced excavator operators make mistakes many times when they have not read how to do.
It is you who will suffer in the first place if the function is deficient.
It is therefore wise to ensure that the installation of your sewerage system is done correctly, that the components have the right function and that the right materials are used.
By law, the contractor has a 10-year functional guarantee on the installation, and unfortunately there are many products sold on the market that do not work.
Be careful when choosing a product and contractor, then the system will work well for many years.
As the property owner, you are always responsible for the function. It does not matter that it is approved by the environmental office the week before, if the treatment does not work.
Every week we get questions about spare parts that don’t exist for a supplier that no longer exists, choose products from well-known manufacturers that have been on the market for a long time and are financially sound.
When designing an individual sewerage system, the following must be taken into account:
– Household size.
– Soil conditions, terrain and soil types
– Groundwater conditions
– Topography and slope conditions
– Proximity to water source
– Depth to bedrock
– Topography of the bedrock
– Proximity to a lake or watercourse
– Climate and soil frost conditions
– Local regulations
– Proximity to road
– Distance to property boundaries (neighbors)
– Ventilation in the house
– Distance for the sludge truck
– Drinking water purification technology
– Energy boreholes nearby
– Size of bathtub
– Water quality of drinking water
The municipality’s environmental and health protection office will come after the application and inspect the intended site for the sewage plant.
Often, test excavation is required for so-called sieve analysis or percolation test, i.e. measurement of the size distribution of soil particles.
The analysis is also done to study groundwater conditions, which determines the ability of the wastewater to penetrate into surrounding soil layers.
The distance between the infiltration level and the groundwater surface shall be at least 1 m, except for short periods (maximum 2 months in a year). The distance between the infiltration level and the groundwater surface shall never be less than 0,5 m.
Sand and macadam for infiltration
The quality of the sand and macadam materials used should follow the instructions in the Swedish Environmental Protection Agency’s publication “Small sewage plants”. The environmental protection office in the municipalities often has good knowledge of where you can obtain the right materials for your infiltration or soil bed. The macadam must be washed to avoid clogging of pipes and bed. Otherwise, the lifetime of the system may be shortened. The material separating the layers of the bed should be finer gravel, such as garden shingle. Above the bed, non-woven fabric is used to separate the backfill material (humus) from the macadam.
General advice
Sewage pipes, sludge separators and distribution wells should be filled with sand or fine gravel. Pack carefully. The slope must be carefully measured with a spirit level.
The slope of the spreader pipes in particular must be exactly as specified. Ensure that surface water is drained away above the infiltration and soil bed.
Sludge separators must be emptied at least once a year. The spreader pipe and any collection pipe must be terminated above ground level with ventilation hoods.
Please note! House drains shall be vented on the roof of the house above the ridge. Vacuum valves shall not be used.
Sludge separator
The function of the sludge separator is to make the flow as slow as possible, so that the coarsest particles sink to the bottom of each chamber and grease and oil rise to the surface. The water is then discharged via a distribution well for treatment in the infiltration bed or in the soil bed.
Location on the site
The sludge separator must be placed so that it can be easily accessed by sludge suction vehicles, normally a maximum of 10 meters. Otherwise, a sludge suction pipe may be installed.
The sludge separator or bed must not be placed so that it is passed by vehicles that cause increased ground pressure.
To reduce the risk of clogging, take advantage of the topography so that the soil pipes from the house have a smooth fall, avoid unnecessary bends.
We recommend that a cleanout be installed on the sewer line just outside the house foundation and every 20-30 meters. This facilitates flushing of the line in the event of a blockage.
The infiltration or soil bed for a normal household takes up an area of about 16-30 m2. If biomodules are used, the area will be smaller.
The total area for a complete plant with sludge separator, infiltration bed and wells etc. is easily 50-100 m2
Keep in mind that the life span of the bed is about 15 years, when choosing the location.
Infiltration or ground bed – what should I have?
Infiltration bed
Is the most common type of post-treatment stage. The ability of the soil to receive the wastewater determines whether such a facility can be used.
In the infiltration bed, treatment takes place at the bottom of the macadam layer, the sand and in the surrounding soil layers.
An infiltration or soil bed facility can be constructed as a uniform field, in which case the distance between pipes is 1.5 m. Alternatively, they can be constructed as separate trenches with a pipe spacing of approximately 2 m.
Soil bed
In cases where the soil’s absorption capacity is poor,
for example due to high groundwater, proximity to mountains or excessively dense soil layers such as clay, the water must instead be treated in a soil bed and then discharged into the environment. The soil bed consists of a sand bed where the wastewater is filtered and treated and then drained away and led away.
Sometimes you have to make the soil bed tight with a large rubber sheet around all sides except the top.
How to install infiltration and soil bed systems
Described from the top down, but of course the installation is built from the bottom up.
1. Spreading layer
The spreading layer is an approximately 30-40 cm thick washed macadam layer with a grain size of 12-24 or 16-32 mm.
The bottom of the trench should be level and smooth, but not compacted no trampling and no vehicles.
The trench may be common to several spreader pipes or provided with a separate trench for each pipe. The separate trenches may be directed in different directions from the distribution well.
2. Spreader pipes
The bottom of the trench is leveled to form a base for the macadam layer.
The spreader pipes are placed in the macadam layer (gray edge upwards) so that the fall of the pipes is 0.5-1 cm/m and so that at least 30 cm of macadam is under the pipes at the end. At least 5 cm of macadam (12-24 or 16-32 mm) shall cover the pipes. The total thickness of the macadam layer is 30-40 cm.
Bends are installed at the outlet ends of the pipes, and aeration pipes are connected to them, which should reach above the snow cover in winter.
The distance between the spreader pipes in the same direction in separate strings shall be at least 2 m. The distance between the pipes in a common shaft shall be at least 1.5 m. The maximum length of each individual spreader pipe is 15 m. The pipes are extended with joint sleeves.
Finally, lay the fleece on the macadam and backfill the shaft.
3. Filtration layer
The filtration sand is placed under the spreading layer. The phosphorus is bound to the sand and the organic substances are broken down in the bio layer. The filtration layer is made of sand with a grain size of 0-8 mm. The thickness of the layer is about 85 cm. On top of the filtration layer there is a distribution layer, with spreader pipes, fiber cloth and filling soil.
4. Collection layer (only for soil beds)
The collection layer is the bottom layer of the soil bed and its task is to collect the treated wastewater, which is then led in collection pipes to the outlet well.
The collection layer uses collection gravel with a grain size of 8-16 mm. The thickness of the collection layer is approximately 30 cm.
5. collecting pipes
Collecting pipes are drainage pipes with holes all around through which the treated water is led away. The collection pipes are laid in the collection layer with a slope of 0.5-1.0 cm/m.
At the ends of the collection pipes, bends for aeration pipes are placed well above the ground surface. Aeration hoods are fitted to the aeration pipes
6. Outlet well (only in case of soil bed)
The collection pipes are led to an outlet well which also serves as a sampling well.
Level an outlet well bed to the correct level. Place the outlet well vertically and fill sand around the well.
7. Outlet pipe
The treated water is led from the collection well through an outlet pipe
(110 mm) to a suitable place in the terrain, e.g. an open ditch.
If the level differences on the plot are not sufficient for self-fall, the treated water must be pumped to the outlet point.
The outlet of the discharge pipe should be fitted with a stone coffin to protect against ice plugs and prevent small animals such as rodents from entering the system.
8. Sealed soil bed
A sealed soil bed is constructed by laying a rubber sheet around the entire shaft for the soil bed. Rubber sheets prevent wastewater from entering the groundwater.
A rubber sheet measuring approximately 15 x 7.5 m is laid out along the bottom of the trench.
The rubber sheet is also laid over the ends of the trench. Make sure that the rubber sheet is not damaged when it is laid out. The edge must not be turned in over the soil bed, as this prevents the air supply to the microorganisms
in the soil.
9. Pumping
It is very common to have to pump the wastewater. It is easier to pump the water after the sludge separator and this can be done in two ways, with a pump integrated into the sludge separator or in a separate pump well.
It can be good to have a level alarm that warns if the pump is not working properly.
Usually 32-40 mm PEM hose is used from the pump to the distribution well or directly into the spreader pipe.
If possible, install a straight 110 mm pipe with self-draining 1-2 meters before the distribution well. This will dampen the incoming flow.
The pump should be fitted with a non-return valve to prevent water from flowing backwards when the pump is not in operation. Many starts and stops on a pump are what shorten the ‘life’ of the pump.
If the pressure pipe cannot be installed frost-free, frost protection type: insulation and often heating cable must be installed.
Please note! The pump well shall be vented between the distribution well and the pump well
Self-inspection
Sludge separator
When emptying sludge, the chambers must be emptied in order; first, second and last third chamber. This is to avoid any sludge escaping between
the chambers. After emptying, the sludge separator must be filled with water in reverse order.
At least once a year, preferably in conjunction with sludge emptying, it is a good idea to inspect the sludge separator visually. Check the lid and the lock, but also, if possible, inside the separator, for any fouling. Rinse if necessary.
Sludge stop filter is a good accessory that is inserted in the outlet T-pipe of the sludge separator that prevents sludge from going out and clogging the bed.
Distribution well
Once a year the distribution well should be inspected.
If there is a lot of sludge in the well, it means that there is something wrong with the system.
Check the lid and lock. Fouling can form in the distribution well. If there is little growth, it can be flushed away.
If there are large amounts, you should try to collect most of it and then flush because of the risk of clogging. This is an indication that the distribution well needs to be inspected at more frequent intervals.
Pump and pump well
The pump should be inspected and maintained according to the pump manufacturer’s instructions. Check the function of the non-return valve to avoid “backflow” in the system.
On the pump well, it is important to check the cover, locking and connections between the pump and the PEM pipe.
If in doubt about the function/condition of the electrical connection, contact an electrician.
Infiltration/collection pipes
These pipes can be inspected through the air pipes. Insert a stick/rod into the pipes to check that there is no water in the pipes. If there is water in the pipes, the bed is not working properly.
The high water may be due to temporary or constant change in groundwater conditions. This must be monitored until the water subsides. If there is still water in the pipe at normal low water, the installation must be drained or rebuilt.
Check that the air pipes and ventilation hoods are not blocked.
Outlet well
Check that the lid and lock are intact.
Is the water in this well colored and smelly?
Then your soil bed is not working properly and should be fixed.
Level alarm
The sensor for the alarm is lifted and flushed clean. Test the function of the alarm.
Service diary
Do not forget to note sludge emptying and ongoing maintenance in the service diary.
This facilitates troubleshooting and fulfills the requirements for self-monitoring according to general advice.
Product details
Article number:
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Installation instructions for infiltration & soil beds
Read more about our infiltration beds & soil beds at this link
Infiltration is by far the most common form of treatment technology in Sweden. Soil beds are used where the ground is too dense to be infiltrated. Dense soil beds are used when no water can or must be discharged where the bed is placed and in cases where all water must be led through a phosphorus trap after treatment in the bed.
Building an infiltration or soil bed does not look so difficult, but unfortunately there are an incredible number of installations of infiltration beds in Sweden that work very poorly.
There are many different opportunities to make mistakes, even experienced excavator operators make mistakes many times when they have not read how to do.
It is you who will suffer in the first place if the function is deficient.
It is therefore wise to ensure that the installation of your sewerage system is done correctly, that the components have the right function and that the right materials are used.
By law, the contractor has a 10-year functional guarantee on the installation, and unfortunately there are many products sold on the market that do not work.
Be careful when choosing a product and contractor, then the system will work well for many years.
As the property owner, you are always responsible for the function. It does not matter that it is approved by the environmental office the week before, if the treatment does not work.
Every week we get questions about spare parts that don’t exist for a supplier that no longer exists, choose products from well-known manufacturers that have been on the market for a long time and are financially sound.
When designing an individual sewerage system, the following must be taken into account:
– Household size.
– Soil conditions, terrain and soil types
– Groundwater conditions
– Topography and slope conditions
– Proximity to water source
– Depth to bedrock
– Topography of the bedrock
– Proximity to a lake or watercourse
– Climate and soil frost conditions
– Local regulations
– Proximity to road
– Distance to property boundaries (neighbors)
– Ventilation in the house
– Distance for the sludge truck
– Drinking water purification technology
– Energy boreholes nearby
– Size of bathtub
– Water quality of drinking water
The municipality’s environmental and health protection office will come after the application and inspect the intended site for the sewage plant.
Often, test excavation is required for so-called sieve analysis or percolation test, i.e. measurement of the size distribution of soil particles.
The analysis is also done to study groundwater conditions, which determines the ability of the wastewater to penetrate into surrounding soil layers.
The distance between the infiltration level and the groundwater surface shall be at least 1 m, except for short periods (maximum 2 months in a year). The distance between the infiltration level and the groundwater surface shall never be less than 0,5 m.
Sand and macadam for infiltration
The quality of the sand and macadam materials used should follow the instructions in the Swedish Environmental Protection Agency’s publication “Small sewage plants”. The environmental protection office in the municipalities often has good knowledge of where you can obtain the right materials for your infiltration or soil bed. The macadam must be washed to avoid clogging of pipes and bed. Otherwise, the lifetime of the system may be shortened. The material separating the layers of the bed should be finer gravel, such as garden shingle. Above the bed, non-woven fabric is used to separate the backfill material (humus) from the macadam.
General advice
Sewage pipes, sludge separators and distribution wells should be filled with sand or fine gravel. Pack carefully. The slope must be carefully measured with a spirit level.
The slope of the spreader pipes in particular must be exactly as specified. Ensure that surface water is drained away above the infiltration and soil bed.
Sludge separators must be emptied at least once a year. The spreader pipe and any collection pipe must be terminated above ground level with ventilation hoods.
Please note! House drains shall be vented on the roof of the house above the ridge. Vacuum valves shall not be used.
Sludge separator
The function of the sludge separator is to make the flow as slow as possible, so that the coarsest particles sink to the bottom of each chamber and grease and oil rise to the surface. The water is then discharged via a distribution well for treatment in the infiltration bed or in the soil bed.
Location on the site
The sludge separator must be placed so that it can be easily accessed by sludge suction vehicles, normally a maximum of 10 meters. Otherwise, a sludge suction pipe may be installed.
The sludge separator or bed must not be placed so that it is passed by vehicles that cause increased ground pressure.
To reduce the risk of clogging, take advantage of the topography so that the soil pipes from the house have a smooth fall, avoid unnecessary bends.
We recommend that a cleanout be installed on the sewer line just outside the house foundation and every 20-30 meters. This facilitates flushing of the line in the event of a blockage.
The infiltration or soil bed for a normal household takes up an area of about 16-30 m2. If biomodules are used, the area will be smaller.
The total area for a complete plant with sludge separator, infiltration bed and wells etc. is easily 50-100 m2
Keep in mind that the life span of the bed is about 15 years, when choosing the location.
Infiltration or ground bed – what should I have?
Infiltration bed
Is the most common type of post-treatment stage. The ability of the soil to receive the wastewater determines whether such a facility can be used.
In the infiltration bed, treatment takes place at the bottom of the macadam layer, the sand and in the surrounding soil layers.
An infiltration or soil bed facility can be constructed as a uniform field, in which case the distance between pipes is 1.5 m. Alternatively, they can be constructed as separate trenches with a pipe spacing of approximately 2 m.
Soil bed
In cases where the soil’s absorption capacity is poor,
for example due to high groundwater, proximity to mountains or excessively dense soil layers such as clay, the water must instead be treated in a soil bed and then discharged into the environment. The soil bed consists of a sand bed where the wastewater is filtered and treated and then drained away and led away.
Sometimes you have to make the soil bed tight with a large rubber sheet around all sides except the top.
How to install infiltration and soil bed systems
Described from the top down, but of course the installation is built from the bottom up.
1. Spreading layer
The spreading layer is an approximately 30-40 cm thick washed macadam layer with a grain size of 12-24 or 16-32 mm.
The bottom of the trench should be level and smooth, but not compacted no trampling and no vehicles.
The trench may be common to several spreader pipes or provided with a separate trench for each pipe. The separate trenches may be directed in different directions from the distribution well.
2. Spreader pipes
The bottom of the trench is leveled to form a base for the macadam layer.
The spreader pipes are placed in the macadam layer (gray edge upwards) so that the fall of the pipes is 0.5-1 cm/m and so that at least 30 cm of macadam is under the pipes at the end. At least 5 cm of macadam (12-24 or 16-32 mm) shall cover the pipes. The total thickness of the macadam layer is 30-40 cm.
Bends are installed at the outlet ends of the pipes, and aeration pipes are connected to them, which should reach above the snow cover in winter.
The distance between the spreader pipes in the same direction in separate strings shall be at least 2 m. The distance between the pipes in a common shaft shall be at least 1.5 m. The maximum length of each individual spreader pipe is 15 m. The pipes are extended with joint sleeves.
Finally, lay the fleece on the macadam and backfill the shaft.
3. Filtration layer
The filtration sand is placed under the spreading layer. The phosphorus is bound to the sand and the organic substances are broken down in the bio layer. The filtration layer is made of sand with a grain size of 0-8 mm. The thickness of the layer is about 85 cm. On top of the filtration layer there is a distribution layer, with spreader pipes, fiber cloth and filling soil.
4. Collection layer (only for soil beds)
The collection layer is the bottom layer of the soil bed and its task is to collect the treated wastewater, which is then led in collection pipes to the outlet well.
The collection layer uses collection gravel with a grain size of 8-16 mm. The thickness of the collection layer is approximately 30 cm.
5. collecting pipes
Collecting pipes are drainage pipes with holes all around through which the treated water is led away. The collection pipes are laid in the collection layer with a slope of 0.5-1.0 cm/m.
At the ends of the collection pipes, bends for aeration pipes are placed well above the ground surface. Aeration hoods are fitted to the aeration pipes
6. Outlet well (only in case of soil bed)
The collection pipes are led to an outlet well which also serves as a sampling well.
Level an outlet well bed to the correct level. Place the outlet well vertically and fill sand around the well.
7. Outlet pipe
The treated water is led from the collection well through an outlet pipe
(110 mm) to a suitable place in the terrain, e.g. an open ditch.
If the level differences on the plot are not sufficient for self-fall, the treated water must be pumped to the outlet point.
The outlet of the discharge pipe should be fitted with a stone coffin to protect against ice plugs and prevent small animals such as rodents from entering the system.
8. Sealed soil bed
A sealed soil bed is constructed by laying a rubber sheet around the entire shaft for the soil bed. Rubber sheets prevent wastewater from entering the groundwater.
A rubber sheet measuring approximately 15 x 7.5 m is laid out along the bottom of the trench.
The rubber sheet is also laid over the ends of the trench. Make sure that the rubber sheet is not damaged when it is laid out. The edge must not be turned in over the soil bed, as this prevents the air supply to the microorganisms
in the soil.
9. Pumping
It is very common to have to pump the wastewater. It is easier to pump the water after the sludge separator and this can be done in two ways, with a pump integrated into the sludge separator or in a separate pump well.
It can be good to have a level alarm that warns if the pump is not working properly.
Usually 32-40 mm PEM hose is used from the pump to the distribution well or directly into the spreader pipe.
If possible, install a straight 110 mm pipe with self-draining 1-2 meters before the distribution well. This will dampen the incoming flow.
The pump should be fitted with a non-return valve to prevent water from flowing backwards when the pump is not in operation. Many starts and stops on a pump are what shorten the ‘life’ of the pump.
If the pressure pipe cannot be installed frost-free, frost protection type: insulation and often heating cable must be installed.
Please note! The pump well shall be vented between the distribution well and the pump well
Self-inspection
Sludge separator
When emptying sludge, the chambers must be emptied in order; first, second and last third chamber. This is to avoid any sludge escaping between
the chambers. After emptying, the sludge separator must be filled with water in reverse order.
At least once a year, preferably in conjunction with sludge emptying, it is a good idea to inspect the sludge separator visually. Check the lid and the lock, but also, if possible, inside the separator, for any fouling. Rinse if necessary.
Sludge stop filter is a good accessory that is inserted in the outlet T-pipe of the sludge separator that prevents sludge from going out and clogging the bed.
Distribution well
Once a year the distribution well should be inspected.
If there is a lot of sludge in the well, it means that there is something wrong with the system.
Check the lid and lock. Fouling can form in the distribution well. If there is little growth, it can be flushed away.
If there are large amounts, you should try to collect most of it and then flush because of the risk of clogging. This is an indication that the distribution well needs to be inspected at more frequent intervals.
Pump and pump well
The pump should be inspected and maintained according to the pump manufacturer’s instructions. Check the function of the non-return valve to avoid “backflow” in the system.
On the pump well, it is important to check the cover, locking and connections between the pump and the PEM pipe.
If in doubt about the function/condition of the electrical connection, contact an electrician.
Infiltration/collection pipes
These pipes can be inspected through the air pipes. Insert a stick/rod into the pipes to check that there is no water in the pipes. If there is water in the pipes, the bed is not working properly.
The high water may be due to temporary or constant change in groundwater conditions. This must be monitored until the water subsides. If there is still water in the pipe at normal low water, the installation must be drained or rebuilt.
Check that the air pipes and ventilation hoods are not blocked.
Outlet well
Check that the lid and lock are intact.
Is the water in this well colored and smelly?
Then your soil bed is not working properly and should be fixed.
Level alarm
The sensor for the alarm is lifted and flushed clean. Test the function of the alarm.
Service diary
Do not forget to note sludge emptying and ongoing maintenance in the service diary.
This facilitates troubleshooting and fulfills the requirements for self-monitoring according to general advice.
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