Most septic tanks for private use are made up of two parts: the sludge containment and digestion tanks and the dispersion layer. This article describes a rather small system, which can be used by a maximum of two people, but cannot withstand the drains of the washing machine; uses a different concept than large septic tanks; the tank is much smaller than necessary and the project does not include some important elements, such as the internal foam protection and a professional survey of the installation site. The plant uses two 210-liter bins instead of those of 3800 or 7500 liters that are normally used; moreover, it provides a dispersion layer about one third of the size that is installed in a house for a large family.
People who plan to use a septic tank like this for their home should remember that this type of installation does not meet any requirement defined by municipal public health regulations and could be subject to heavy fines; however, it is always better to dispose of waste properly rather than abandon it. Modern toilet flushes currently use less than eight liters of water per flush and this septic tank can handle that volume. For people who live in an area where there is no sewage system, this system can be a real "lifesaver".
Steps
Step 1. Dig a trench 120cm wide, 8m long and 1m deep
Step 2. Gather all the materials, parts and equipment
In this regard, consult the "Things You Will Need" section.
Step 3. Make a hole in the top of each stem
It must have a diameter equal to the outside diameter of the toilet flange and be close to the edge; for this operation it is better to use a hacksaw.
Step 4. Attach a 10cm flange to each hole
Step 5. Drill two holes in the top of the lower barrel wall as shown in the image
They must form a 45 ° angle to the perpendicular line joining the first hole to the side.
Step 6. Cut a hole in the wall of the upper barrel, so that it is perpendicular to the first hole, as shown in the figure
Step 7. Place the container with a single hole on the wall at the end of the moat
Make sure it is level and at least 10cm below the edge of the pit.
Step 8. Dig a hole about 30 cm deep in front of the first bin to insert the second
Step 9. Continue digging that hole a little longer and partially fill it with gravel
Your goal is to level the two containers, so that the 90 ° corner joint fits snugly into the hole in the wall of the first bin and into the toilet flange installed on the lid of the second bin.
Step 10. Cut a 9 cm long segment of ABS pipe that has a diameter of 10 cm and glue it to one end of the 90 ° joint
Cut another segment about 6.5 cm long and glue it to the other end.
Step 11. Do a test to test the alignment between the two stems
The end of the shorter hose must engage in the tallest bin; in the end you should get a structure similar to the one shown in the figure.
Step 12. Once the assembly has been checked, glue the end of the 9cm hose into the toilet flange
You will seal the hose to the top bin later.
Step 13. Join the left arm of the "Y" joint to a 9 cm pipe and the 45 ° joint
Then line up the joint itself so that it joins the waste duct and glue it to the toilet flange.
Step 14. Cut and glue two 6.5 cm segments to one end of each of the two remaining 45 ° joints
Insert them into the two holes that are on the wall of the lower bin as shown in the image; the joints must be perpendicular to the pit.
Step 15. Verify that the assembly is as shown in the image
Step 16. Drive a peg into the ground so that the top is at the same height as the bottom edge of one of the 45 ° joints
Step 17. Attach a 2.5cm block of wood to the end of a 120cm level
Use duct tape and refer to the attached image.
Step 18. Plant the second peg just under 120cm from the first
Step 19. Place the end of the level without a wooden block on the first peg and the one with the piece of wood on the second
Tap the stake until the level shows that it is in line with the first; at this point, the second rung should be 2.5 cm lower than the first, with a slope of 6 mm every 30 cm.
Step 20. Repeat the procedure until you have planted all the stakes the full length of the pit
Step 21. Put the gravel in the pit until it reaches the top of the stakes
Step 22. The crushed stone should have a slope of 6 mm every 30 linear cm
Step 23. Join two perforated 3m and 10cm diameter drainage pipes using adapters
Make the holes face down and connect one end to one of the 45 ° joints; repeat the process with the other pair of tubes and the other joint.
Step 24. Check the drainage pipes with the spirit level and wooden block to make sure they meet the slope along their entire length
Make any changes by adding or removing gravel.
Step 25. Seal the 45 ° and 90 ° joints to their respective bins using two-component epoxy glue or silicone
Refer to the image related to this step to understand where to spread the glue; Consider using slightly flexible hoses, so they will adjust in case the ground gives way a little.
Step 26. If the sealant needs to cure, fill the bins with water to prevent them from being crushed by the pressure of the crushed stone
Bury everything up to the top of the lower stem using more gravel.
Step 27. Spread an outdoor tarp over the crushed stone
This way, you prevent the earth from infiltrating the gravel.
Step 28. Continue filling the pit with soil compacting it well until it reaches the same level as the surrounding area
Step 29. Fill the top bin with water
Advice
- Instead of using a 90 ° elbow joint, you should mate two to get a "U" piece; in this way, the end of the first barrel points towards the bottom of the tank. Add a short straight segment of pipe by extending it slightly to a greater depth. Solid waste can float or sink, but it does not remain suspended in mid-water and therefore never reaches the second bin which only fills with liquids. You should follow the same method for each drainage tube coming from the second drum to be absolutely sure there are no leaks to the outside.
- It is assumed that you know how ABS pipes are handled; you must also have the proper equipment to dig the pit (otherwise you will have to work hard).
- The depth of the pit depends on that of the plant from which the waste comes. If the latter is higher or lower than described in the article, you need to vary the depth of the excavation. It is not difficult to make an accurate assessment; remember that if the pit is too shallow, the implant can be easily damaged.
- The horizontal arm of the "Y" joint connects to the waste supply pipe and should be equipped with a suitable adapter.
- After some time you may notice that the pit area gives way slightly as the earth stabilizes; add more soil and compact it with the wheels of the car. Do not drive over the area where the bins are buried.
- The vertical arm of the "Y" joint should be used to empty the tank when it is completely full of solid waste.
- The Imhoff tank consists of two 210-liter plastic bins. The waste fills the first tank and the solid part falls towards the bottom; when the liquid reaches the drain level, it falls into the second container. If there are solids, they move towards the bottom; when the liquid material reaches the discharge level of the second bin, it is dispersed through the gravel layer. Most solid waste liquefies over time and is dispersed; after a couple of years it completely fills the tank which must be emptied.
- 30% of the waste is dispersed in the ground while 70% evaporates due to the effect of sunlight; do not compact the soil because it hinders the evaporation process.
Warnings
- Avoid building the septic tank near trees because roots can develop along the pipes and cause an obstruction; over time they can damage the system.
- Comply with local regulations regarding the construction of a sewer system. You cannot install one without permission; the municipal technical office provides you with all the details to comply with the laws.
- The one described in this article is a plant with a very small capacity. It is not designed to meet the needs of a large family, but only for small caravans inhabited by two people. To maximize the life of this small pit, do not throw anything into the system except water, feces and toilet paper; if not, you need to empty the top bin once a year; this type of pit must be emptied twice every five years.
