Monolithic septic tank made of concrete with your own hands

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Monolithic septic tank made of concrete with your own hands
Monolithic septic tank made of concrete with your own hands

The device is a monolithic septic tank made of concrete. Applicability of cast cleaners depending on their design. Seamless concrete sump construction technology.

How to make a monolithic septic tank out of concrete?

Pouring the bottom of a monolithic concrete septic tank

Consider the construction technology of the most popular cast septic tank - a two-chamber one. The work is carried out in three stages: digging a foundation pit, making the formwork, pouring concrete. Let's consider all the stages in more detail:

  • Determine the dimensions of a monolithic septic tank made of concrete, based on SNiP standards. In our case, the purifier is designed for 5 people, has a size of 2x3 m and a depth of 2.3 m.
  • Dig a pit of the required size. The monolithic septic tank consists of two sections, but one digs the hole. You can dig it out in 1-2 days. Check the horizontality of the bottom and verticality of the walls with a level, so it is advisable to use an excavator only at the initial stage of work.
  • Fill the bottom with quarry sand with a layer of 20 cm. On top of it, add a layer of crushed stone 10 cm thick of the medium fraction with the size of stones 50 mm.
  • Cover the bottom and walls of the pit with plastic wrap and temporarily fix it in any way so as not to be blown away by the wind. The edges of the canvas should protrude beyond the pit. The film performs two tasks: it reduces the consumption of concrete and additionally waterproofs the septic tank.
  • The bottom can not be insulated with a film and not concreted, but covered with porous or loose material that allows water to pass through well. In this case, the liquid will seep into the ground, which will increase the intervals between the arrivals of the sewage truck. Often they dig deep pits and then cover them with a grid with a very fine mesh. From above, everything is covered with crushed stone with a layer of 15-20 cm. Thus, the productivity of the septic tank is increased.
  • Reinforce the bottom by securing the mesh at a distance of 7 cm from the floor.
  • Prepare a concrete solution from cement grade not lower than M300 and sand, which are taken in a ratio of 1: 3. The amount of water should be such that the mixture is moderately thick. Add liquid plasticizer, the amount depends on the brand of cement.
  • Fill the bottom with mortar, wait until it hardens.
  • Mark the position of the formwork walls around the pit perimeter. The transverse partition should split the pit in two. The first has dimensions of 1.7x1.7 m, the second - 1.7x0.85 m.
  • Place a reinforcing mesh inside the future walls and secure in an upright position. You can make it yourself from fittings, knitting wire, or use factory-made devices. It should be in the middle of the wall.
  • Collect formwork 15-20 cm thick around the perimeter of the pit. It is made of moisture-resistant chipboard - a durable and inexpensive building material. To avoid buying a lot of sheets, use sliding formwork. It is mounted up to half the height of the pit, poured with concrete, and then lifted and mounted on an already hardened partition. This method allows you to evenly distribute the concrete during pouring and tamp it. Fasten the shields to wooden beams.
  • Install wooden supports on the outside to increase the rigidity of the structure.
  • Dig a trench from the house to the foundation pit. Its depth should be below the level of soil freezing in your area, otherwise the sewer pipe will have to be insulated.
  • Make a hole in the formwork for the drainage from the house. Pass a sewer pipe into it and put on an L-shaped pipe that will direct the drains down.
  • In the wall formwork between the chambers, make a hole connecting the two tanks.It should be 40-50 cm below the entrance opening. Install a pipe about 40 cm long into it and fix it on both sides of the wall. Slide the two downward sleeves onto the pipe. This location of the inlet will not allow solid inclusions to move into the second compartment.
  • Fill the septic tank with concrete. To prevent voids from forming, fill the solution in layers no more than 500 mm high.
  • After compacting the layer with a construction vibrator, continue filling the formwork. For the convenience of feeding the thick mixture into a narrow slot, use a chute made of half of the pipe. Fill all walls in 1 day. Fast filling of the trench will eliminate the formation of boundaries between layers that have hardened on different days. These walls will last longer.
  • Further work can be continued after complete hardening of the concrete, at least 28 days. To keep the walls dry evenly, cover them with damp burlap or plastic.
  • After reaching the maximum strength of the walls, dismantle the formwork.
  • Examine the constructed structure. If cracks and potholes are found, grout them with cement mortar.
  • To create the upper floor of a cast septic tank made of concrete, install metal corners around the perimeter of the structure: one on the wall and 2 pieces each. on the jumper between the tanks.
  • Additionally, place the corners for the hatches on top - you should get openings through which a person can crawl.
  • Drill a hole in the walls and corners and secure the frame to the base with anchors.
  • Measure the dimensions of the windows in the frame and cut the slabs from the flat slate along them.
  • Lay the workpieces on the corners, leaving the hatch openings uncovered.
  • For waterproofing, apply liquid bitumen to the joints of the slabs.
  • Place two rows of reinforced mesh on the floor.
  • Fence the hatch openings with boards. Also expose the formwork over the entire floor area.
  • Carefully cut a hole in the slate above the second chamber and fix the ventilation pipe in it.
  • Make sure the horizontal overlap is strong, because the weight of the concrete is very heavy. If necessary, install wooden supports from below, which are removed after the mortar has hardened.
  • Pour concrete over the floor and leave it to harden. To prevent the wall from cracking, cover it with plastic wrap while the mixture hardens. If work is carried out in winter, take measures to prevent freezing of the solution.
  • Dismantle the formwork after a month. Cover the walls of the building from the inside with waterproofing grease.
  • Fence the openings for the hatches with bricks so that they rise above the ground.
  • Make caps according to the size of the holes. There should be two of them - internal and external. Make the first one out of wood or thick plywood, it is designed to warm the camera. Glue insulation on top of it. The lid must be removable without hinges.
  • Measure the dimensions of the opening above the wooden cover. According to the obtained values, make a frame from the building corner, which should be installed on the bricks enclosing the opening.
  • Install the frame in its original place and secure with anchors.
  • Cut out a sheet for the cover from a sheet of metal 3-4 mm thick. Sand the edges with a sanding attachment. Attach the awnings to the frame on the septic tank and to the canvas and install the hatch in its original place above the opening.
  • Cover the lid with anti-corrosion compound.
  • The final event is backfilling the structure. Fill the gaps between the walls of the septic tank and the pit with a mixture of excavated soil, cement and clay. Pour the soil in layers with a thickness of 30-40 cm, and then compact it. On top of the sump, first cover with expanded clay, and then with earth. A hatch with a cover should protrude above the surface.

How to make a monolithic septic tank from concrete - watch the video:

From our article it is clear that making a monolithic septic tank from concrete with your own hands is not difficult. Such a structure is simple and reliable and will last for many years.However, in order to save yourself from repair work, you must follow the construction technology and follow the recommendations of the professionals given above.

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