Storm (rain) sewage is a type of drainage system that removes runoff from the service area in a timely manner. Depending on the conditions of use, such systems may have a different set of functional components, differ in dimensional parameters and protective additions. In terms of areas of application, the storm sewer system is used in the arrangement of city streets, in the infrastructure of industrial facilities and in the engineering and communication support of private households.
Sewage structure
Like any other plumbing infrastructure, storm sewers operate on the basis of pipeline networks. With the help of pipes, water passes from one functional point of the system to another. The working cycle begins from the sections with storm water inlets, which carry out local collection of water. In this capacity, trays with chutes often act. They are mounted in ditches for drainage in such a way that the drains can be directed by gravity to the distribution manifold. A variety of storm water inlets is also a door tray. Such devices are installed either at the gate or near the entrance tohouse.
Without fail, the installation of storm sewer systems provides for the presence of capacitive water storage. These are devices that accumulate water collected in primary water intakes. They can be implemented in different ways, but the main task remains the same - to ensure sufficient surface water intake to eliminate the risk of flooding the territory.
Cleaning function of the storm sewer system
Unlike a septic tank that accepts household waste and sewage, rainwater drainage does not require deep biological treatment. Of course, there are systems in which the septic tank also acts as a receiver for storm drains. And in this case, cleaning will completely depend on the capabilities of this tank. A septic tank can act both as a simple storage without cleaning functions, and as a means of multi-stage filtration. Separating the tasks of a septic tank and storm sewer just makes sense because of the different requirements for cleaning. Rainwater may well be discharged into the ground without the danger of disturbing the ecological state of the soil. However, basic filtration is still required to protect the drainage system itself. Therefore, the storm sewer cleaning system often includes sand traps that trap large soil particles, debris and stones. That is, mechanical cleaning filters are used that prevent physical contamination of the pipeline, storage tank and collector units.
Classification by methoddrainage system
At the moment, there are three types of sewer systems designed for rainwater. First of all, this is a ditch configuration with open drain channels. Such systems are usually used in cities and can perform several tasks, including drainage and irrigation of landscape gardening areas. Structurally, such networks are formed by systems of ditch concrete trays located along roads and streets. Ditch trays are distinguished by a perforated surface that allows passive distribution of water over the soil cover. Also, an external storm sewer system can also be used in the arrangement of private households with plots, but this solution will be ineffective. In urban environments, an open system is beneficial just because of its high performance, as it works with large volumes of water. But in a small area, a closed system option is more effective. In this configuration, water runoff is collected in trays that are part of the landscape array. In other words, the pipeline network is placed in a soil niche and covered with protective devices. The third option is a combined design in which open and closed sections replace each other depending on the conditions for passing the drainage circuit.
Classification by configuration of water tanks
Both open and closed sewer systems differ in the way water collectors are organized. In point schemes, receiving funnels with gratings are installed separately from each other. That is, small undergroundor ground tanks in accordance with the most intensive flow of water. In this case, all points of the water collectors are combined into a single network directed to the reservoir. An alternative way is a linear layout of collectors. Thus, a continuous drainage and storm sewer system is formed on the site, which, already in the process of collection, combines several sources of water supply. Otherwise, the equipping of rainwater collection and drainage channels is carried out according to general principles with the integration of filters, collector units and gratings.
Rain drain design
Even stormwater for small areas should be arranged on the basis of a design solution in which pumping lines, points of collection, distribution and accumulation of water are calculated. Moreover, the basis for the project can be developed independently, by determining the most likely sources of water spills and the optimal place for its reception. The plan will have to include the contours of the drains, the placement of communications, equipment and storage. More serious projects of the drainage system and storm sewers also provide for the implementation of geodetic surveys of the area. One of the main objects of analysis will be the level of groundwater occurrence, which will determine the optimal location of the drainage system and the reservoir, which ensures the discharge of wastewater directly into the ground.
Installation of pipeline and related equipment
Pipes are desirable to useplastic, as they do not corrode, are easy to install and require little or no maintenance. Laying is carried out in a trench, the bottom of which is previously covered with sand, gravel and covered with geotextiles. Next, the formed network should be wrapped in geotextile so that the drainage filler completely covers the surface of the pipes. Connections are made using complete couplings of the appropriate size. Then the functional units of the collectors, the collector and the receiver are arranged, with which the storm sewer system will interact. In this case, installation must be carried out with observance of a slope towards the place of accumulation of water. So, for 1 m, about 1-2 cm of slope should be provided. The same applies to networks in which the main sewer network will be the final collection point. It is not worth filling up the channels until the pipeline has been tested in working conditions.
Installation of sewer cover
The easiest way to cover a trench with a storm sewer channel is backfilling with the same excavated soil. But for this, you should make sure that the line is reliably sealed, and there are layers of sand and gravel in its structure. If the channel passes through critical functional areas on the site, then additional reinforcement may be required. Under the paths, parking areas and the entrance of vehicles, additional reinforcement must be installed. For this, overlappings can be used, which in the future are also covered with a dense layer of soil. Buteven at the stage of installing a storm sewer system, it is recommended to calculate the load on the network using the appropriate pipes. In particular, it is recommended to lay a non-perforated metal pipe under the road for a car. The use of plastic is also allowed, but in an armored shell. Drainage and geotextile layers are made in the same way as on the other contours.
Organization of a security zone near the sewers
Hydrological resources that provide water supply, in accordance with the norms of SNiP, are introduced into special protection zones. The same rules apply to sewers. If we are talking about urban and public areas, then the radius of such areas should be about five meters. Of course, in a private household, strict adherence to this standard is not required, but it will still be useful to support some of the principles by which the storm sewer system with the adjacent area is protected. In particular, it is forbidden to build temporary structures near canals, arrange garbage dumps, break flower beds and plant trees.
Storm drain cleaning
Regardless of type and location, storm drains should be flushed regularly. To do this, pumps are used, installed at the places of collection of water. In the household, you can get by with one unit, rearranging it in turn to each circuit leading to the place of water accumulation. The pump is connected to the local water supply system and is directed by a pressure jet alongchannel towards the slope. The flow eliminates contaminants in confined spaces that cannot be physically reached. Also, the rules for using the storm sewer system require separate cleaning of the storage tank. Moreover, the internal surfaces must be regularly subjected to chemical disinfection in order to maintain the proper sanitary and environmental condition of the territory.
Features of the care of the drainage system
The drainage system associated with the sewer outlet requires a special approach to maintenance. First of all, the upper layer of the drain should always be kept loose - this way it absorbs and passes water into the soil more efficiently. For the same reason, it is not recommended to walk on mounds of sand and gravel, and even more so to use heavy equipment on them. If the drainage and storm sewer system at the site is connected to intermediate wells and collector nodes, then they should be cleaned of dirt and sand in a separate order. It is desirable that this work be carried out automatically using pumped washers with floats.
Conclusion
The variety of sanitary equipment for the garden allows you to organize a variety of rainwater sewer configurations. The most reliable option would be a system in which a closed network (trench) is implemented, supplemented by trays, wells, a collector and filter membranes. As for the cleaning function, the drainage and storm sewer system can be connected to the septic tank, which, in itsturn, will perform multi-stage biological wastewater treatment. But, again, directly storm drains and do not require fine filtration. It is enough to provide the system with high-quality sand traps and gratings that trap large debris. Another thing is that these components of the sewer system will require regular manual cleaning, otherwise there will be a risk of clogging of the channels and subsequent flooding of the site.
