q20 value.

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Notes: 1. Specific average daily water disposal may be changed by 10-20% depending on climatic and other local conditions and the degree of improvement.

2.10. 2. In the absence of data on industrial development beyond 1990, it is allowed to accept additional wastewater flow from enterprises in the amount of 25% of the flow determined according to table. 3. Gravity lines, collectors and channels, as well as pressure pipelines of domestic and industrial wastewater should be checked for the passage of the total calculated maximum flow rate according to paragraphs. 2.7 and 2.8 and additional influx of surface and groundwater during periods of rain and snowmelt, unorganizedly entering the sewerage network through leaks in well hatches and due to groundwater infiltration. The amount of additional inflow q ad

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula Where L

- total length of pipelines to the calculated structure (pipeline site), km;T d

- the value of the maximum daily precipitation, mm, determined in accordance with SNiP 2.01.01-82.

A verification calculation of gravity pipelines and channels with a cross section of any shape for the passage of increased flow must be carried out at a filling height of 0.95.

2.11. ESTIMATED RAINWATER EXPENSES Rainfall costs q r

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula , l/s, should be determined using the limiting intensity method using the formula z mid

- the average value of the coefficient characterizing the surface of the drainage basin, determined in accordance with clause 2.17; A, p

- parameters determined in accordance with clause 2.12; F

- estimated runoff area, hectares, determined in accordance with clause 2.14; t r

- estimated duration of rain, equal to the duration of surface water flow through the surface and pipes to the design area, min, and determined in accordance with clause 2.15. Estimated rainwater flow for hydraulic calculation of rainwater networks q cal

, l/s, should be determined by the formula

Notes: 1. If the estimated duration of rainwater flow is less than 10 minutes, a correction factor of 0.8 should be entered into formula (2) at - estimated runoff area, hectares, determined in accordance with clause 2.14;= 5 min and 0.9 at - estimated runoff area, hectares, determined in accordance with clause 2.14;= 7 min.

2. If the initial sections of rainwater sewer collectors are deeply buried, one should take into account the increase in their throughput due to the pressure created by rising water levels in the wells.

2.12. Options A And P should be determined based on the results of processing long-term records of self-recording rain gauges registered at a given location. If there is no processed data, the parameter is allowed A determine by formula

(4)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula q 20 - rain intensity, l/s per 1 ha, for a given area for a duration of 20 minutes at R= 1 year, determined by lines. 1;

P- exponent determined according to table. 4;

- total length of pipelines to the calculated structure (pipeline site), km;r- average amount of rain per year, taken according to the table. 4;

R- the period of one-time excess of the calculated rain intensity, accepted according to clause 2.13;

g is the exponent taken according to the table. 4.

Crap. 1. Rain intensity values q 20

Table 4

2.13. The period of one-time excess of the calculated rain intensity must be selected depending on the nature of the sewerage facility, the conditions of the location of the collector, taking into account the consequences that may be caused by rainfall exceeding the calculated ones, and taken according to the table. 5 and 6 or determined by calculation depending on the conditions of the collector location, rain intensity, basin area and runoff coefficient for the maximum period of excess.

When designing rainwater drainage for special structures (metro, stations, underground passages, etc.), as well as for arid areas, where the importance q 20 less than 50 l/(s×ha), with R, equal to one, the period of one-time excess of the calculated rain intensity should be determined only by calculation, taking into account the maximum period of exceeding the calculated rain intensity specified in Table. 7. In this case, periods of one-time excess of the calculated rain intensity, determined by calculation, should not be less than those indicated in the table. 5 and 6.

When determining the period of a single excess of the calculated rain intensity by calculation, it should be taken into account that with the maximum periods of a single excess specified in Table. 7, the rain sewer collector must pass only part of the flow of rainwater, the rest of which temporarily floods the roadway of the streets and, if there is a slope, flows down its trays, while the height of the flooding of the streets should not cause flooding of basements and semi-basements; in addition, possible runoff from pools located outside the populated area should be taken into account.

2.11. Rainfall costs q r, l/s, should be determined using the limiting intensity method using the formula

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula z mid- the average value of the coefficient characterizing the surface of the drainage basin, determined according to clause 2.17;

- the average value of the coefficient characterizing the surface of the drainage basin, determined in accordance with clause 2.17;- parameters determined according to clause 2.12;

- parameters determined in accordance with clause 2.12;- estimated runoff area, hectares, determined according to clause 2.14;

t r- the estimated duration of rain, equal to the duration of the flow of surface water along the surface and pipes to the design area, min, and determined according to clause 2.15.

Estimated rainwater flow for hydraulic calculation of rainwater networks q cal, l/s, should be determined by the formula

(3)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula b- coefficient that takes into account the filling of the free capacity of the network at the moment of pressure regime occurrence and is determined by table eleven.

Notes: 1. If the estimated duration of rainwater flow is less than 10 minutes, formula (2) a correction factor of 0.8 should be entered when t r= 5 min and 0.9 at t r= 7 min.

2. If the initial sections of rainwater sewer collectors are deeply buried, one should take into account the increase in their throughput due to the pressure created by rising water levels in the wells.

2.12. Options A And P should be determined based on the results of processing long-term records of self-recording rain gauges registered at a given location. If there is no processed data, the parameter is allowed A determine by formula

(4)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula q 20 - rain intensity, l/s per 1 ha, for a given area for a duration of 20 minutes at R= 1 year, determined by crap. 1;

P- exponent determined by table 4;

- total length of pipelines to the calculated structure (pipeline site), km; r- average amount of rain per year received according to table 4;

R- the period of one-time excess of the calculated rain intensity, taken according to clause 2.13;

g- exponent taken according to table 4.

Crap. 1. Values ​​of rain intensity q20

Table 4

2.13. The period of one-time excess of the calculated rain intensity must be selected depending on the nature of the sewerage facility, the conditions of the location of the collector, taking into account the consequences that may be caused by rainfall exceeding the calculated ones, and taken according to table 5 And 6 or determined by calculation depending on the conditions of the collector location, rain intensity, basin area and runoff coefficient for the maximum period of excess.

When designing rainwater drainage for special structures (metro, stations, underground passages, etc.), as well as for arid areas, where the importance q 20 less than 50 l/(s×ha), with R, equal to unity, the period of a single excess of the calculated rain intensity should be determined only by calculation, taking into account the maximum period for exceeding the calculated rain intensity specified in table 7. In this case, periods of one-time excess of the calculated rain intensity, determined by calculation, should not be less than those specified in table 5 And 6 .

When determining the period of one-time excess of the calculated rain intensity by calculation, it should be taken into account that with the maximum periods of one-time excess specified in table 7, the rain sewer collector should pass only part of the flow of rainwater, the rest of which temporarily floods the roadway of the streets and, if there is a slope, flows down its trays, while the height of the flooding of the streets should not cause flooding of basements and semi-basements; in addition, possible runoff from pools located outside the populated area should be taken into account.

Table 5

Notes: 1. Favorable conditions for the location of collectors:

the basin with an area of ​​no more than 150 hectares has a flat topography with an average surface slope of 0.005 or less;

the collector runs along the watershed or in the upper part of the slope at a distance from the watershed no more than 400 m/

2. Average conditions for the location of collectors:

a basin with an area of ​​over 150 hectares has a flat topography with a slope of 0.005 m or less;

the collector runs along the lower part of the slope along the thalweg with a slope slope of 0.02 m or less, while the basin area does not exceed 150 hectares.

3. Unfavorable conditions for the location of collectors:

the collector runs in the lower part of the slope, the basin area exceeds 150 hectares;

the collector runs through the thalweg with steep slopes with an average slope slope of over 0.02.

4. Particularly unfavorable conditions for the location of collectors: the collector removes water from a closed, low place (basin).

Table 6

Note. For enterprises located in a closed basin, the period of one-time excess of the calculated rain intensity should be determined by calculation or taken as a period of at least 5 years.

Table 7

2.14. The calculated drainage area for the calculated section of the network must be taken equal to the entire drainage area or part of it that gives the maximum flow rate.

In cases where the drainage area of ​​the collector is 500 hectares or more, in formulas (2) And ( 3 ) a correction factor should be entered TO, taking into account the unevenness of rainfall over the area and taken according to table 8.

Table 8

Estimated flow rates of rainwater from undeveloped catchment areas over 1000 hectares, not included in the territory of a populated area, should be determined according to the corresponding flow standards for calculating artificial highway structures in accordance with VSN 63-76 Ministry of Transport and Construction.

2.15. Estimated duration of rainwater flow over the surface and pipes t r , min, should be taken according to the formula

(5)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula t con- duration of rainwater flow to the street gutter or, if there are storm water inlets within a block, to the street collector (surface concentration time), min, determined according to clause 2.16;

t can- the same, along street gutters to the storm water inlet (if there are none within the block), determined by formula (6);

t p- the same, along pipes up to the calculated cross-section, determined by formula (7).

2.16. The time of surface concentration of rainwater runoff should be determined by calculation or taken in populated areas in the absence of intra-block closed rainwater networks as 5-10 minutes or in their presence as 3-5 minutes.

When calculating the intra-block sewer network, the surface concentration time should be taken equal to 2-3 minutes.

Duration of rainwater flow through street gutters t can

(6)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula l can- length of tray sections, m;

v can

Duration of rainwater flow through pipes to the calculated cross-section t p, min, should be determined by the formula

(7)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula l p- length of design sections of the collector, m;

v p- estimated current speed in the area, m/s.

2.17. Average runoff coefficient z mid should be determined as a weighted average depending on the coefficients z, characterizing the surface and accepted according to table 9 And 10 .

Table 9

Note. Specified coefficient values z may be specified based on local conditions based on relevant research.

Table 10

2.18. When calculating runoff from basins with an area of ​​more than 50 hectares with different types of development or with sharply different slopes of the ground surface, it is necessary to make test determinations of rainwater flow rates from different parts of the basin and take the highest of the resulting flow rates as the calculated one. Moreover, if the calculated flow rate of rainwater from a given part of the basin turns out to be less than the flow rate at which the collector in the overlying area is designed, the calculated flow rate for this section of the collector should be taken equal to the flow rate in the overlying area.

Territories of gardens and parks that are not equipped with rain closed or open sewerage systems, in the calculated value of the drainage area and when determining the coefficient z are not taken into account. If the territory has a surface slope of 0.008-0.01 or more towards street passages, then the calculated drainage area must include a strip 50-100 m wide adjacent to the passage.

Green areas within blocks (strips of boulevards, lawns, etc.) should be included in the calculated value of the drainage area and taken into account when determining the coefficient of the drainage basin surface z.

2.19. Coefficient values b should be determined by table eleven.

Table 11

Notes: 1. For terrain slopes of 0.01-0.03, the specified coefficient values b should be increased by 10-15% and for terrain slopes greater than 0.03 should be taken equal to one.

2. If the total number of sections on a rain collector or tributary is less than 10, then the value b for all slopes it is allowed to reduce by 10% when the number of sections is 4-10 and by 15% when the number of sections is less than 4.

2.11. Rainfall costs q r, l/s, should be determined using the limiting intensity method using the formula

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula z mid- the average value of the coefficient characterizing the surface of the drainage basin. determined in accordance with clause 2.17;

- the average value of the coefficient characterizing the surface of the drainage basin, determined in accordance with clause 2.17; - parameters determined in accordance with clause 2.12;

- parameters determined in accordance with clause 2.12; - estimated runoff area, hectares, determined in accordance with clause 2.14;

t r- estimated duration of rain, equal to the duration of surface water flow through the surface and pipes to the design area, min, and determined in accordance with clause 2.15.

Estimated rainwater flow for hydraulic calculation of rainwater networks q cal, l/s, should be determined by the formula

where  - coefficient that takes into account the filling of the free capacity of the network at the moment the pressure regime occurs and is determined from table. eleven.

Notes: 1. For the estimated duration of rainwater flow. less than 10 minutes, a correction factor of 0.8 should be entered into formula (2) at t r = 5 min and 0.9 at t r = 7 min.

2. If the initial sections of rainwater sewer collectors are deeply buried, one should take into account the increase in their throughput due to the pressure created by rising water levels in the wells.

2.12. Options A And P should be determined based on the results of processing long-term records of self-recording rain gauges registered at a given location. If there is no processed data, the parameter is allowed A determine by formula

(4)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula q 20 - rain intensity, l/s per 1 ha, for a given area for a duration of 20 minutes at P = 1 year, determined by lines. 1;

P- exponent determined according to table. 4;

- total length of pipelines to the calculated structure (pipeline site), km; r - average amount of rain per year, taken according to table. 4;

R - the period of one-time excess of the calculated rain intensity, accepted according to clause 2.13;

 - exponent taken according to the table. 4.

Crap. 1. Values ​​of rain intensity q20

Table 4

2.13. The period of one-time excess of the calculated rain intensity must be selected depending on the nature of the sewerage facility, the conditions of the location of the collector, taking into account the consequences that may be caused by rainfall exceeding the calculated ones, and taken according to the table. 5 and b or determined by calculation depending on the conditions of the collector location, rain intensity, basin area and runoff coefficient for the maximum period of excess.

When designing rainwater drainage for special structures (metro, stations, underground passages, etc.), as well as for arid areas, where the importance q 20 less than 50 l/(sha), with R, equal to one, the period of one-time excess of the calculated rain intensity should be determined only by calculation, taking into account the maximum period of exceeding the calculated rain intensity indicated in Table. 7. In this case, periods of one-time excess of the calculated rain intensity, determined by calculation, should not be less than those indicated in the table. 5 and 6.

When determining the period of a single excess of the calculated rain intensity by calculation, it should be taken into account that with the maximum periods of a single excess specified in Table. 7, the rain sewer collector must pass only part of the flow of rainwater, the rest of which temporarily floods the roadway of the streets and, if there is a slope, flows down its trays, while the height of the flooding of the streets should not cause flooding of basements and semi-basements; in addition, possible runoff from pools located outside the populated area should be taken into account.

Table 5

Notes: 1. Favorable conditions for the location of collectors:

the basin with an area of ​​no more than 150 hectares has a flat topography with an average surface slope of 0.005 or less;

the collector runs along a watershed or in the upper part of a slope at a distance from the watershed no more than 400 m,

2. Average conditions for the location of collectors:

a basin with an area of ​​over 150 hectares has a flat topography with a slope of 0.005 m or less;

the collector passes through the lower part of the slope along the thalweg with a slope slope of 0.02 m or less, while the basin area does not exceed 150 hectares.

3. Unfavorable conditions for the location of collectors:

the collector runs in the lower part of the slope, the basin area exceeds 150 hectares;

the collector runs through the thalweg with steep slopes with an average slope slope of over 0.02.

4. Particularly unfavorable conditions for the location of collectors: the collector removes water from a closed, low place (basin).

Table 6

Note. For enterprises located in a closed basin, the period of one-time excess of the calculated rain intensity should be determined by calculation or taken as a period of at least 5 years.

Table 7

2.14. The calculated drainage area for the calculated section of the network must be taken equal to the entire drainage area or part of it that gives the maximum flow rate.

In cases where the drainage area of ​​the collector is 500 hectares or more, a correction factor should be entered into formulas (2) and (3) TO, taking into account the unevenness of rainfall over the area and taken according to the table. 8.

Table 8

Estimated flow rates of rainwater from undeveloped catchment areas over 1000 hectares, not included in the territory of a populated area, should be determined according to the corresponding flow standards for calculating artificial highway structures in accordance with VSN 63-76 of the Ministry of Transport.

2.15. Estimated duration of rainwater flow over the surface and pipes t r , min, should be taken according to the formula

(5)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula t con- duration of rainwater flow to the street gutter or, if there are storm water inlets within a block, to the street collector (surface concentration time), min, determined in accordance with clause 2.16;

t can- the same, along street gutters to the storm water inlet (if there are none within the block), determined by formula (6);

t p- the same, along pipes to the calculated cross-section, determined by formula (7),

2.16. The time of surface concentration of rain runoff should be determined by calculation or taken in populated areas in the absence of intra-block closed rain networks equal to 5-10 minutes or in the presence of them equal to 3-5 minutes.

When calculating the intra-block sewer network, the surface concentration time should be taken equal to 2-3 minutes.

Duration of rainwater flow through street gutters t can

(6)

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula l can- length of tray sections, m;

v can

Duration of rainwater flow through pipes to the calculated cross-section t p, min, should be determined by the formula

, l/s, should be determined on the basis of special surveys or operating data of similar objects, and in their absence - according to the formula l p- length of design sections of the collector, m;

v p- estimated current speed in the area, m/s.

2.17. Average runoff coefficient z mid should be determined as a weighted average depending on the coefficients z, characterizing the surface and accepted according to the table. 9 and 10.

Table 9

Ground surfaces (planned) z Note. Specified coefficient values

Table 10

2.18. When calculating runoff from basins with an area of ​​more than 50 hectares with different types of development or with sharply different slopes of the ground surface, it is necessary to make test determinations of rainwater flow rates from different parts of the basin and take the highest of the resulting flow rates as the calculated one. Moreover, if the calculated flow rate of rainwater from a given part of the basin turns out to be less than the flow rate at which the collector in the overlying section is designed, the calculated flow rate for this section of the collector should be taken equal to the flow rate in the overlying section.

Territories of gardens and parks that are not equipped with rain closed or open sewerage systems, in the calculated value of the drainage area and when determining the coefficient z are not taken into account. If the territory has a surface slope of 0.008-0.01 or more towards street passages, then the calculated drainage area must include a strip 50-100 m wide adjacent to the passage.

Green areas within blocks (strips of boulevards, lawns, etc.) should be included in the calculated value of the drainage area and taken into account when determining the coefficient of the drainage basin surface z.

2.19. The values ​​of the coefficient  should be determined from the table. eleven.

Table 11

Notes: 1. For terrain slopes of 0.01-0.03, the specified values ​​of the coefficient  should be increased by 10-15% and for terrain slopes over 0.03 taken equal to one.

2. If the total number of sections on a rain collector or on a tributary is less than 10, then the value of  for all slopes can be reduced by 10% when the number of sections is 4-10 and by 15% when the number of sections is less than 4.

Surface runoff is formed by rain and melt water, as well as water from watering and washing streets. At the same time, precipitation from rain and melt water in cities produces runoff at a layer of more than 2 mm due to the presence of large areas of waterproof coatings (coverings of courtyards, roadways of streets, roofs of houses).

Hydraulic calculations of the drainage system must be carried out for each site and area individually; such calculations are best entrusted to specialists designing drainage and sewerage systems. Gidrolica® surface drainage systems are designed to collect and drain water from the surface of road surfaces, as well as from the foundations of buildings and structures. Our company’s specialists can give you recommendations on the selection of Gidrolica® drainage systems.

Let's consider one of the simplified calculation options. In order to choose the right drainage tray, it is necessary to calculate the amount of precipitation that fell on the estimated area. Water consumption Q l/s per area is calculated using the formula:

Q = q 20 × F × ϕ

Where:
q 20– precipitation intensity (l/sec) per Ha (Ha = 10,000 m2);
- parameters determined in accordance with clause 2.12;– calculated drainage area in m2;
ϕ – coefficient of water absorption of the coating surface;

Example:
It is necessary to select a Gidrolica® drainage tray
Coating type ( ϕ ): asphalt – 0.95 (see table drainage surface coefficient).
Precipitation intensity ( q 20) – Moscow region – 80 (l/sec) per hectare (see table precipitation intensity).

Drain surface coefficient

Substituting the available data into the formula, we obtain the amount of precipitation in a given region that needs to be collected.

Q = 80 × 0.06 × 0.95 = 4.56 (l/sec)

According to the obtained indicator Q(throughput) we select a drainage tray from the catalog, according to the load class. In our case, trays DN 100, class. C250 (see general characteristics of the tray)

General characteristics of trays

To effectively release water into sewer networks, it is necessary to take into account the throughput of the pipes (see the throughput of pipes at various slopes, l/sec).

The type of foundation for pipes must be taken depending on the bearing capacity of the soil and loads (see SNiP 2.04.03-85)

Pipe capacity at various slopes, l/sec