What is a protected zone of water supply?
The sanitary and sanitary protection zone is a sanitary protection zone provided for the environmental protection of water supply facilities. Includes 3 protection belts:
- high security belt (No. 1);
- restrictive belt (No. 2);
- observational belt (No. 3).
In the zone of strict regime, as a rule, the water intake facilities and water intake facilities are located. It is designed to protect them from any harm, intentional or unintentional. It is determined in accordance with established standards and procedures. No strangers are allowed in this zone, and the territory itself is guarded by armed guards.
In the zone of the first belt, any construction, excavation, storage of materials, the use of fertilizers, waste disposal, cutting down of green spaces, grazing of livestock, fishing, swimming and boating are prohibited.
A restrictive belt is necessary to protect the water from contamination by microbes, infections and viruses.It starts right behind the first belt. In this territory it is strictly forbidden to locate any industrial and agrotechnical buildings, factories, fields and pastures, to carry out construction, to arrange beaches and recreation areas.
In addition, no explosive works, vibration work (driving piles), waste disposal, mining, deforestation, storage of toxic chemicals, fertilizers and fuels and lubricants, plowing virgin lands and draining of swamps should not be carried out on the territory of belt No. 2.
Observation belt is designed to control chemical contamination of water. Inside it does not provide for any restrictions, but the territory needs constant monitoring by the sanitary-epidemiological services.
The last 2 belts (second and third) are calculated by hydrodynamic scientists individually for each water intake. The calculations are rather complicated, therefore, to simplify them, various computer programs were created. For example, modules for calculating zones of sanitary protection AMWELLS.
All specified sanitary zones must be marked on the maps, marked with warning signs and information signs on the ground.The territory of strict regime should be enclosed with a solid fence with barbed wire, and on the water - be marked with buoys with illumination.
Approximate methods for defining protection zones
An open or surface water intake source is rivers, lakes, artificial reservoirs and other terrestrial sources of water. In the case of water supply from an open source, the strict mode belt is calculated based on the actual location of the head elements of the water supply system (water intake structures).
In order to outline the first security belt of the water supply system from the head elements of the water supply system, it is measured 180–200 m against the flow of water and 90–100 m downstream. This zone also includes the coastal strip. Depending on the power of the current and the size of the river, the belt of strict regime enters from 50 to 200 m, often with the seizure of the opposite bank.
The following method is used to determine the first protection zone around the water intake on a lake or artificial reservoir (reservoir). From the head elements of the water intake in all directions are measured at 100m so that we get a circle that runs partially through the water and partially over the land.On the water, the security zone is marked with buoys and buoys illuminated at night.
An approximate calculation of the territory of the second belt is based on the ability of river water to self-purification. It is believed that the average river is cleared of contaminants that have fallen into it within 3-5 days. Consequently, during this time, foreign bodies in the water should not be brought in by the flow to the point of intake. Self-purification of water should be guaranteed to occur earlier.
Thus, to calculate the distance to the border of the second belt, the average flow velocity of the river is multiplied by 3-5 days. On average, the figures are as follows: for large rivers - from 20 to 35 km of the channel, for small rivers - from 35 to 60 km above the intake point along the stream. Downstream is usually counted 250-300 m. This is necessary in order to prevent the backflow of water, which sometimes happens, for example, because of the wind.
The third observational zone includes all settlements (cities, towns, villages) feeding on water from this water supply system.
Calculation of security zone in the intake of water from an underground source
In the case of water intake from underground sources (wells), sanitary protection zones are calculated using other methods.If the well that opens the sedimentary aquifer is relatively shallow, the first zone is determined by a circle with a radius of 50 m around the well. Around deep wells, revealing rock, the zone of strict regime is determined by a circle with a radius of 25 m.
On the territory of belt No. 1 it is allowed to locate only the station of the first ascent, the water tower and the minimum required number of outbuildings. Surface and drainage drains are displayed on the border of the first belt. The territory of the first sanitary zone is being landscaped: trees and shrubs are planted, a fence is being built, convenient driveways for transport and special equipment are being laid.
Security zone No. 2 is calculated so that various contaminants from the surface of the earth could not penetrate inside the well to the depth of the aquifer within 100-400 days. Specific indicators and figures are calculated by hydrodynamic scientists with the mandatory consideration of the characteristics of the soil, underground soils and climatic features of the area.
The territory of the observation zone No. 3 includes the nearest infrastructure, buildings and structures where active human activity takes place.It is believed that pollution from this area will move to the water intake so slowly that during this period the well is guaranteed to work out its service life.
Security zones outside the water intake
Around the buildings and structures that are not part of the water intake complex, the sanitary rules and norms of the Russian Federation also provide for protected zones of strict regime:
- around spare tanks and filtration stations - 30 m;
- around settling tanks, pumping stations, premises for storing chlorine and reagents - 15 m;
- around the water towers - 10 m.
Sanitary strips with a width of 10 to 50 m are laid on both sides of the water conduits. The exact value is determined based on the height of the rise of groundwater and the diameter of the water pipes. For example, if the diameter of the pipes is 1 m and less, the width of the sanitary strip should be 10 m. If the diameter of the pipe exceeds 1 m, the width of the guard strips is made equal to 20 m. With high groundwater, the bands widen to 30, 40 and even 50 m.
The width of security zones around water lines can be reduced only when pipes are laid on an already built-up area and with the permission of the sanitary-epidemiological service.
Water protection zone
The network of water pipes in populated areas also has its own security zone, but it is not customary to denote it with signs or signs. You can learn about their location from the plans and schemes of engineering communications, and on the ground - from the wells and hatches of water mains.
First of all, to know the location of water pipes and their sanitary zones is necessary for builders, leading earthworks, laying sewers. So when laying sewer pipes they should not intersect with plumbing. In practice, it is quite difficult to implement, so if they intersect, the water pipe must necessarily be located above the sewer. If this is not possible and the sewage pipe will have to be located above the water supply pipe, a special casing is put on the drain pipe.
At the opening of the soil above the water pipes, it is necessary to observe certain rules of construction work. Earth-moving equipment (excavators and bulldozers) can be used up to a depth of 1 m to the pipe. The same applies to any other impact and vibration instrument.The last meter of soil is removed only manually to avoid damage to the pipes.
In urban areas around the water pipes the following security zones are established:
- for pipes with a diameter of up to 1 m, the zone is 10 m;
- for pipes with a diameter of more than 1 m, the zone is 20 m;
- when laying pipes in wet soils, the protection zone is set at 50 m.
Inside this sanitary zone it is prohibited to lay sewage pipes parallel to water pipes in order to avoid an epidemiological catastrophe if the water lines are damaged.
For thinner pipes of domestic plumbing are less stringent rules. Water pipes should be at a distance of 1.5-5 m from sewer pipes, depending on the material and size of these pipes.
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