First in the world online wastewater calculation calculator presented on our website. The calculator is based on SNIP 2.04.03-85 dated 01/01/1986 — « BUILDING REGULATIONS. Sewerage. External networks and structures."
Thanks to our specialists who have automated the process wastewater calculation, designers and supply managers can save valuable time when calculating stormwater volumes and annual runoff volumes.
In addition, the calculator automatically selects the appropriate one from the OZONE product catalog!

Take advantage wastewater calculation calculator can be found on any page of our website.

Surface runoff calculation

Calculation of surface runoff allows you to obtain accurate data necessary for ordering treatment facilities of the correct capacity. Thanks to the algorithm we developed for calculating the volume of wastewater, the calculation is made in seconds.

Surface runoff calculation program

There are analogues of our program on the market. Unfortunately, competitors prefer to charge fees for installing their software, while our runoff calculation program is completely free and accessible from any device.

Download SNIP 2.04.03-85

For the convenience of our users, we also post the full text of SNIP 2.04.03-85 dated 01/01/1986 — « BUILDING REGULATIONS. Sewerage. External networks and structures"!

Storm drainage is one of the most important equipment systems in a residential area, which, unfortunately, many owners simply forget about or take it too lightly. And it is completely in vain - hopes that rain or melt water will go away by itself often lead to gradual waterlogging of the territory, to the destruction or failure of laid paths and platforms, to erosion and erosion of the foundation structures of erected buildings, waterlogging of their walls and other negative consequences.

Storm sewerage includes many different elements that are responsible for a specific water collection area, for several such areas, or for the entire system as a whole - these are storm inlets, pipes, wells, and collectors. In order for them to be able to cope with their task, their parameters must correspond to the expected volumes of water. And when planning the system, the calculator for calculating the volume of storm drains, which is offered to the reader, may be useful.

Below, under the calculator, a brief explanation of how it works will be given.

December 13 2017

Calculation of external rainwater drainage

An example of storm sewer calculation (Moscow region, Noginsk district). The calculation was carried out according to SP 32.13330.2012.

surface	Area F, ha	% of total F	Coefficient	ψ d (mid)	Coefficient	ψmid
asphalt concrete road surfaces	1,390	0,18	0,60	0,108	0,95	0,171
Roofing of buildings	0,770	0,10	0,60	0,060	0,95	0,094
gravel	0,480	0,06	0,45	0,027	0,30	0,018
Ground surfaces	5,110	0,66	0,100	0,066	0,10	0,066
Total	7,750	1		ψ d (mid) = 0.261		ψ mid =0.349

The average annual volume of surface wastewater W g is determined by:

W g = W d + W t + W m, (formula 4, clause 7.2.1, SP 32.13330.2012)

Where: W d, W t, W m – average annual volume of rain, melt and irrigation water, respectively, m 3

W d = 10h d Ψ d F=10*465*0.261*7.75=9,406.95 m3 (formula 5, clause 7.2.2, SP 32.13330.2012)

W t = 10h t Ψ t K y F=10*225*0.5*1*7.75=8,718.75 m 3 (formula 6, clause 7.2.2, SP 32.13330.2012)

W m = 10mkΨ m F m =10*0.5*150*0.5*7.75=521.25 m 3 (formula 7, clause 7.2.6, SP 32.13330.2012)

W g =9,406.95 +8,718.75 +521.25 =18,646.95 m 3

Where: F is the drainage area of ​​the collector, ha;

K y - coefficient taking into account snow removal (see 7.3.5, SP 32.13330.2012), assumed in the calculation = 1;

h d - precipitation layer, mm, for the warm period of the year, determined according to SP131.13330 (for Moscow = 465 mm);

ht - layer of precipitation, mm, for the cold period of the year (determines the total annual amount of meltwater) or the water reserve in the snow cover at the beginning of snowmelt, determined according to SP131.13330; (for Moscow = 225mm)

Ψ d, Ψ t - the total coefficient of runoff of rain and melt water, respectively

The total runoff coefficient Ψ d for the total runoff area is calculated as a weighted average of the partial values ​​for runoff areas with different surface types according to Table 7.

Table 7 SP 32.13330.2012: - Runoff coefficient values ​​for different types of surfaces

When determining the average annual volume of melt water, the total runoff coefficient Ψ t from residential areas and enterprise sites, taking into account snow removal and water losses due to partial absorption by permeable surfaces during the thaw period, can be taken within the range of 0.5-0.7 (in the calculation, 0. 5).

m is the specific water consumption for washing road surfaces (assumed 0.5 for manual washing and 1.2-1.5 l/m for one mechanized washing);

K is the average number of car washes per year (for central Russia it is 100-150); F m - area of ​​hard surfaces subjected to washing, ha;

Ψ m - runoff coefficient for irrigation water (assumed equal to 0.5)

Volume of rainwater runoff from design rain discharged to treatment facilities:

W very = 10h a Ψ mid F=10*10.0*0.349*7.75=270.7 m 3 (formula 8, SP32.13330.2012)

- h a - the maximum layer of precipitation for rain, the runoff from which is subjected to full purification, mm (we accept from 5-10mm, see Vodgeo);

— Ψ mid — average runoff coefficient for the calculated rain (defined as a weighted average depending on the constant values ​​of the runoff coefficient Ψ i for different types of surfaces according to Table 14, SP 32.13330.2012:

Table 14 SP 32.13330.2012:

Type of drain surface	Cover coefficient	Constant runoff coefficient
Waterproof surfaces (roofs and asphalt concrete surfaces)	0.33-0.23 (accepted according to table 15)	0,95
Cobblestone bridges and crushed stone coverings	0,224	0,6
Cobblestone streets	0,145	0,45
Crushed stone coverings not treated with binding materials	0,125	0,4
Gravel garden paths	0,09	0,3
Ground surfaces (planned)	0,064	0,2
Lawns	0,038	0,1

The maximum daily volume of melt water, in the middle of the snowmelt period, discharged to treatment facilities:

Wt,cyt = 10h s FaΨ t K y =10*25*7.75*0.8*0.5*0.9=697.5 m 3 (formula 9, SP 32.13330.2012)

Where: 10 is the conversion factor;

h c is the layer of melt water for 10 daytime hours at a given supply, we take 25 mm (see Appendix 1, formula 10, Vodgeo);

F- runoff area, ha;

a- coefficient taking into account the unevenness of snow melting can be taken as 0.8;

Ψ t is the total coefficient of melt water runoff (assumed 0.5-0.8), 0.5 is assumed in the calculation;

K y - coefficient taking into account partial removal and removal of snow, determined by the formula:

K y = 1 - Fy /F = 1-0.775/7.75 = 0.9 (formula 10, SP 32.13330.2012)

Fy = 0.15* F=0.1*7.75=0.775

The flow rate of rainwater in rainwater sewer collectors, l/s, will be:

Q r =(Ψ mid *A*F)/t n r =0.349*384.32*7.75/(12.1) 0.59 =327.3 l/s (formula 1, section 7.4, SP 32.13330.2012 )

Where A, n are parameters characterizing, respectively, the intensity and duration of rain for a specific area. A is determined by formula 13, SP 32.13330.2012. n – determined according to Table 9 SP 32.13330.2012.

Ψ mid – average runoff coefficient ( previously calculated)

t n r is the estimated duration of rain, determined by the formula:

tr = t con + t sap + tр =3+0+4.1=7.1 min (formula 14, section 7.4.5, SP 32.13330.2012)

where t con is the duration of rainwater flow to the storm water inlet (surface concentration time), ( determined by SP 32.13330.2012 P. 7.4.6: The time of surface concentration of rainwater runoff should be calculated or taken in populated areas in the absence of intra-block closed rainwater networks equal to 5-10 minutes, and if they are available - equal to 3-5 minutes. When calculating the intra-quarter sewer network, the surface concentration time should be taken equal to 2-3 minutes.). In the calculation, t con = 3 min;

t gland - the same, for street gutters to the storm water inlet (if there are none within the block), determined by formula (15) SP 32.13330.2012. In the calculation it is taken equal to 0, because no street stalls;

t p – the same, along pipes up to the calculated cross-section, determined by:

0.017*410/1.7=7.1, min (formula 16, section 7.4.6, SP 32.13330.2012).

Where: l p - length of design sections of the collector, m (according to the general plan);

V p – estimated current speed in the area, m/s.

80*20 0.59 *(1+lg(0.5)/lg(150)) 1.33 =384.32 (formula 13, SP 32.13330.2012)

Where: q 20 is the intensity of rain, l/s per 1 hectare, for a given area for a duration of 20 minutes at P = 1 year (determined from Figure B.1 SP 32.13330.2012). From Figure B.1 q 20 =80;

m r is the average amount of rain per year (according to Table 9, SP 32.13330.2012). For the flat region of the west and center of the European part of Russia m r =150.;

P-period of a one-time excess of the calculated rain intensity (determined according to clause 7.4.3., table 10,11,12, SP32.13330.2012). In calculation P=0.5;

γ-exponent (determined according to Table 9, SP 32.13330.2012). For the flat region of the west and center of the European part of Russia γ =1.33.

Rainwater flow for hydraulic calculation of rainwater networks:

Qсal = βQr = 0.71*327.3=232.38 l/s

The flow rate of wastewater sent for treatment is determined by formula 167, manual to SNiP 2.04.03-85:

Qg=K1*K2*Qr=0.26*1.51*327.3=128.5l/s

Where: Coefficient values K 1, And K2 depending on size WITH And P for various conditions for calculating treatment facilities and storm drainage networks are given in Table. 55 and 56 manual to SNiP 2.04.0-85), and the parameter values ​​“ n" and coefficient " WITH"in fig. 26, 27 (manual to SNiP 2.04.0-85). For Moscow: C=0.85, n=0.65. We accept P och =0.1. From table 55 (manual for SNiP 2.04.0-85): K 1 =0.26.

Much attention is currently being paid to the removal and purification of surface runoff from urbanized areas. Not a single project can be completed without calculating surface runoff. However, calculating the predicted volumes of surface runoff (calculation of rainfall or calculation of surface runoff) without the use of special software is a rather labor-intensive procedure.

Various methods are used to calculate annual, daily, hourly and second surface runoff flow rates. And to calculate local treatment facilities, it is necessary to calculate not only the flow of wastewater, but also the concentration of pollutants in it (for example, suspended solids or petroleum products). In addition, calculations are often made several times for the same object (for different runoff areas, for different calculated intensities).

In order for you to be able to use your time efficiently, we have developed a program for calculating surface runoff that will do all this work for you within a few minutes. All you need to do is simply enter the initial information for the calculation (runoff areas, calculated intensities and a number of auxiliary parameters).

After entering the initial data, the program allows you to switch to the calculation mode, at the request of the IstokCalc user. RainflowPlus generates a report in Microsoft Word format, made in accordance with current regulatory documents, which you can save, edit, copy, etc.

All calculations (initial data, rain model parameters) are automatically grouped by the program into individual settlements. This allows you to fill in information about the calculated parameters of the rain model for a specific settlement only once, and in the future you can use this data for other objects.

So, the program for calculating surface runoff is IstokCalc. RainflowPlus:

• Determines the estimated flow rates of surface wastewater (rain and melt) using the maximum intensity method;
• Determines the average daily and annual flow rates of surface runoff (rain and melt);
• Determines the concentrations and masses of suspended substances and petroleum products in surface runoff (rain and melt);
• Generates a report in Microsoft Word format, made in accordance with GOST requirements, simulating “manual calculation”, which can be saved, edited, copied, etc.;
• Automatically maintains a general database of your objects and reference books of design parameters. All databases are open for addition, editing, deletion, etc.
• A new version (version 2.0) of the program for calculating surface runoff "RainFlow Plus" is available. A distinctive feature of the new version is the ability to create reports in RTF Microsoft Word format. The ability to create reports using custom templates has been implemented (the only report for the test case is “hardwired” into the demo version).