If a septic tank is used as a wastewater treatment system on the site of your country house, then for its normal operation it is necessary to create a filtration field. It will consist of several trenches with spray pipes located inside. The trenches are filled with gravel, crushed stone and sand, which are necessary to filter the treated effluents. If the work on the design and further organization of such a system was carried out correctly, then there will be no additional problems during the operation and disposal of wastewater.
Field device
After the initial treatment of wastewater from helminths and mechanical impurities has been completed, sewage flows through open channels, moving through a layer of sand. Then they pass into an equipped system of drainage pipes and are discharged into a technical well, river or canal. The presence of air provides the opportunity for bacteria to live. And under their influence, organic waste decomposes into ecological components and harmless elements.
The filtering field is arranged in such a way thatallows the use of an aerobic cleaning process. The efficiency of this system will depend on the composition of the soil that is used for filtration. When developing a project, it is necessary to be guided by sanitary standards, which indicate the need to prevent sewage from entering the water intake systems. The presence of drainage in the filtration field during the operation of a septic tank is mandatory when groundwater occurs at a depth of 1.5 meters from the surface of the earth. A drainage system should also be provided if the underground filtration is in the ground, whose ability to clean up is rather low.
Drafting
Filtration field arrangement begins with project preparation. Particular attention must be paid to the choice of location. It should be located as far as possible from the point of water intake and fruiting shrubs / trees. If these requirements are not met, then harmful substances may end up in the soil, which will negatively affect the quality of berries, water and fruits. The drainage system is capable of operating normally for 7 years or even less, so it must be excavated after this period, cleaned and replaced with crushed stone, soil and sand that serve to filter.
When a filtration field is set up, it is important to carry out a calculation that takes into account the depth of the sand layer to a mark below the freezing line. Otherwise, at low temperatures, the filtration fields will not be able to perform their functions.
Settlements
If you decide to equip the filtration field, which is necessary for a septic tank of concrete rings, then you can consider the example below. According to the conditions on the site - sandy soil, and groundwater occurs at a depth of 2 meters. The capacity of the septic tank per day is one cubic meter. It is necessary to calculate the length of the irrigation pipe under the mentioned conditions.
You also need to find out what the average annual temperature is in your area. For the Moscow region, this figure is 3 degrees. With a two-meter occurrence of groundwater and an average annual temperature of less than 6 degrees, the load per 1 meter of pipe will be 20 liters. This indicates that field equipment with an irrigation pipe length of 50 meters will be required. If soil filling is taken into account, then the load on the pipes is taken with a factor ranging from 1.2 to 1.5. This indicates that wastewater treatment systems should have irrigation pipes that are 41.7 meters long (50/1, 2).
Filtration field device technology
Biological wastewater treatment at the site will be carried out effectively if you create a filtration field that consists of underground pipes and ditches. A layer of soil 10 centimeters thick is laid at the bottom of the dug hole, which will pass moisture well. The next layer will be sand of the same thickness. At this stage, it is necessary to lay drainage pipes with holes, which will create an effective filtration field.
When the described wastewater treatment systems are built,the use of flexible pipelines is not recommended, otherwise the environmental regulations will be violated. Each ditch should have a platform with crushed stone, the layer thickness is 40 centimeters. From above, everything is covered with textile material, which is designed to protect the drainage system from pollution and low temperatures. The area under which the filtration field is located must be covered with earth.
Expert Tips
If you are interested in the question of how water treatment plants are created, then you should familiarize yourself with certain rules. One of them says that complete biological treatment can be achieved if the field is located on sand, sandy loam or light loam. If the territory is on clay soil, then the field will not be effective, since clay is not able to pass moisture. As practice shows, in this case, the cost of the work will be quite high compared to the installation of finished treatment facilities. Indeed, in this case, clay will have to be removed to the location of the sand layer.
What else you need to know before starting work
Water treatment facilities of the described type operate on the principle of soil self-purification. But this ability is not unlimited, therefore, during the work, it is necessary to build additional cleaning systems. If you consume water in large quantities, then an artificial reservoir can be planted to dispose of wastewater from the drainage system. There it will bepurified liquid flow. During the day, adult birch trees that should be planted around will consume about 100 liters of water, this will eliminate the overflow of the artificial reservoir. A septic tank filtration field will last longer if the effluents entering it are as clean as possible.
Possible causes of field clogging
Biological treatment may fail, which will become clear when the system stops absorbing water. This can lead to silting of the soil. Unfortunately, this process cannot be stopped, but it is quite possible to slow it down. The main thing at the same time is to exclude poorly cleaned sewage from entering the field. If the drainage layer quickly filled with silt, then unscheduled cleaning and filter replacement work will have to be carried out. Otherwise, the septic tank will overflow the edge of the structure.
Conclusion
If you want the filtration field to work as efficiently as possible, it is best to equip it on light loam, sandy loam or sandy soil. In the latter case, the load per meter of irrigation pipes will be 30 liters per day. As for sandy loamy soils, this figure will be halved. In loams, this value is even less, so during the work it will be necessary to lengthen the pipes and make the thickness of the crushed stone layer much larger.
For laying the pipeline, be sure to choose the most rigid perforated drainage or sewer pipes. At the same time, the presence of a sand filter is important, which will clean the system of remaining impurities and foreign inclusions.
