The external sewer network is designed based on the total wastewater flow. To calculate it, water disposal standards are used.

The norm for the disposal of household wastewater is the average daily conventional volume of such water, which falls on one resident of the facility subject to sewerage. The norm is measured in liters.

For process wastewater, this amount is calculated relative to one unit using water according to the process flow chart.

For residential properties, water disposal standards are usually equated to water consumption standards. This is due to the fact that household wastewater is essentially used tap water, contaminated during its use for domestic needs. Not all water supplied to the consumer water supply network can enter the domestic sewer network. This is the volume that is used for washing technical equipment and cooling them, road surfaces, watering green spaces, feeding fountains, etc. When taking this into account, the water disposal rate should be reduced by this share.

Water disposal standards are regulated by SNiP P-G.1-70. Their values ​​depend on local climate conditions and others: the presence or absence of internal water supply, sewerage, centralized hot water supply, water heaters for baths, etc.

Water consumption varies not only with the season of the year, but also with the time of day. Water drainage should also change in the same regime. The hourly unevenness of the flow of wastewater into the sewer depends on its total volume. The greater the total consumption, the less this unevenness is felt.

Coefficients of unevenness of water disposal

When designing a sewer system, it is necessary to proceed not only from the standard and total volumes of wastewater that can be discharged. It is important to take into account fluctuations in the daily water disposal regime. The system must cope with wastewater discharge during peak hours. This also applies to all its parameters, for example the power of fecal pumps. To calculate maximum flow rates, appropriate corrections are used - coefficients of unevenness of water drainage.

A granularity of calculation of unevenness of water drainage up to one hour is required only for objects with a high probability of unevenness. In other cases, possible hourly unevenness is taken into account in the previously accepted reserve in the volume of pipes. When making hydraulic calculations of pipeline sections, their filling is assumed to be partial in advance.

The coefficient of daily unevenness kcyt of water disposal is the ratio of the daily maximum wastewater flow Q max.day to the daily average flow Q avg.day for the year:

k day = Q max.day / Q average day

The coefficient of hourly unevenness khour of water disposal is determined similarly:

k hour = Q max.hour / Q average hour

Here Q max.hour and Q average hour are the maximum and average hourly costs. Q average hour is calculated based on the consumption per day (dividing it by 24).

By multiplying these coefficients, the coefficient of general unevenness ktot is calculated: drainage

k total = k day k hour

General coefficients depend on the average costs and are given in the corresponding tables for designers.

To calculate this coefficient for values ​​of average flow rate that are not in the tables, interpolation is used based on their closest data. The formula proposed by Professor N.F. Fedorov is used:

ktot = 2.69 / (q avg)0.121.

The value qср is the wastewater flow rate in 1 second (average second) in liters.

The formula is valid for average second flow rates up to 1250 liters. The coefficient of daily unevenness of water drainage for public buildings is taken as one.

The hourly unevenness coefficient for technological wastewater strongly depends on production conditions and is very diverse.

I calculate the costs of shower wastewater from an industrial enterprise:

Average daily Q shower day = (40N 5 + 60N 6)/1000, m 3 / day, (4.12)

Hour after each shift Q shower hour = (40N 7 + 60N 8)/1000, m 3 / h, (4.13)

Second q shower sec = (40N 7 + 60N 8)/45 * 60, l/s, (4.14)

where N 5, N 6 are, respectively, the number of people using a shower per day with a water disposal rate per person in cold shops of 40 liters and 60 liters in hot shops;

N 7, N 8 – respectively, the number of people using a shower per shift with maximum water removal in cold and hot shops.

Q shower day = (40 * 76.8 + 60 * 104.5)/1000 = 9.34 m 3 /day,

Q shower hour = (40 * 48 + 60 * 66.5)/1000 = 5.91 m 3 /h,

q shower sec = (40 * 48 + 60 * 66.5)/45 * 60 = 2.19 l/s.

Fill out form 4.

If Form 4 is filled out correctly, the value of the second consumption of domestic wastewater calculated using formula (4.11) should be equal to the sum of the largest expenses from the 7th column;

q life max = 0.43 l/s and (0.16 + 0.27) = 0.43 l/s.

And the value of the second flow rate of shower drains (4.14) is the sum of the highest costs from the last column;

q shower sec = 2.19 l/s and (0.71 + 1.48) = 2.19 l/s.

I determine the estimated consumption from an industrial enterprise:

q n = q industrial + q life max + q shower sec, l/s,

q n = 50.3 + 0.43 + 2.19 = 52.92 l/s.

Calculation of costs at sites.

I divide the drainage network into design sections and assign a number to each node (well) of the network. Then I fill out columns 1-4 of form 5.

I determine the flow rate at each design site using the formula:

q cit = (q n + q side + q mp)K gen . max + q sor, l/s, (4.16)

where q n is the travel flow rate entering the design area from residential buildings located along the route;

q side – side, coming from the side connections

q mp – transit, coming from upstream sections and equal in value to the total average flow rate of previous sections;

q сср – concentrated flow from public and municipal buildings, as well as industrial enterprises located above the design site;

Kgen. max – overall maximum unevenness coefficient.

I take the value of average costs (columns 5-7 of form 5) from previously filled out form 1. The total cost (column 8) is equal to the sum of travel, lateral and transit costs on the site. You can check that the total flow rate (from column 8) must be equal to the average flow rate per area (form 1, column 3).

To determine the unevenness coefficient, I construct a smooth graph of changes in the coefficient value depending on the average wastewater flow. I take the points for the graph from the table. 4.5. For average flow rates less than 5 l/s, the estimated costs are determined in accordance with SNiP 2.04.01-85. The overall maximum unevenness coefficient for areas with a flow rate of less than 5 l/s will be equal to 2.5.

The values ​​of the total maximum unevenness coefficient determined from the constructed graph are entered in column 9 of Form 5.

Table 4.5

General coefficients of unevenness of domestic water inflow.

I multiply the values ​​in columns 8 and 9 and get the estimated expense for the quarter. Columns 11 and 12 contain concentrated costs, which can be classified as either lateral (costs directed to the beginning of the site) or transit (costs from upstream buildings). Concentrated expenses can also be checked; their sum is equal to the calculated second expenses from Form 2.

In the last column I summarize the values ​​from columns 10,11,12.

Graph for determining the coefficient of unevenness (it is on graph paper). Remove this sheet later; it is needed for page numbering.

Plot no.	Codes of drainage areas and numbers of network sections	Average consumption, l/s	Overall maximum unevenness coefficient	Estimated flow rate, l/s
Way howl	Side	Transit	Traveler	Side	Transit	General	From quarters	Concentrated	Total
Side	Transit
1-2		-	-	3,96	-	-	3,96	2,5	9,9	0,26	-	10,16
2-3		-	1-2	4,13	-	3,96	8,09	2,16	17,47	2,23	0,26	19,96
3-4		-	2-3	3,17	-	8,09	11,26	2,05	23,08	0,33	2,49	25,9
4-5		-	3-4	3,49	-	11,26	14,75	1,94	28,62	1,4	2,82	32,84
6-7		-	-	0,80	-	-	0,80	2,5	2,0	-	-	2,0
7-8		-	6-7	3,58	-	0,80	4,38	2,5	10,95	0,37	-	11,32
8-9	-	-	7-8	-	-	4,38	4,38	2,5	10,95	-	0,37	11,32
9-14		8-9	-	1,33	4,38	-	5,71	2,42	13,82	-	0,37	14,19
12-13		-	-	1,96	-	-	1,96	2,5	4,9	-	-	4,9
13-14		-	12-13	0,90	-	1,96	2,86	2,5	7,15	-	-	7,15
14-15		9-14	13-14	1,44	5,71	2,86	10,01	2,1	21,02	-	0,37	21,39
10-15		-	-	3,05	-	-	3,05	2,5	7,63	0,33	-	7,96
15-16	-	10-15	14-15	-	3,05	10,01	13,06	2,0	26,12	-	0,7	26,82
11-16		-	-	1,13	-	-	1,13	2,5	2,83	-	-	2,83
16-21		15-16	11-16	0,81	13,06	1,13	15,0	1,96	29,4	-	0,7	30,1
21-26		-	16-21	4,01	-	15,0	19,01	1,90	36,12	-	0,7	36,82
20-25		-	-	2,39	-	-	2,39	2,5	5,98	2,23	-	8,21
28-25		-	-	2,44	-	-	2,44	2,5	6,1	0,26	-	6,36
25-26	-	28-25 20-25	-	-	2,44 2,39	-	4,83	2,5	12,08	-	2,49	14,57
26-27		25-26	21-26	2,60	4,83	19,01	26,44	1,6	42,3	0,33	3,19	45,82
5-27	-	4-5	-	-	14,75	-	14,75	1,96	28,91	-	4,22	33,13
27-34		5-27	26-27	2,67	14,75	26,44	43,86	1,71	75,0	-	7,74	82,74
30-29		-	-	2,44	-	-	2,44	2,5	6,1	1,28	-	7,38
29-34	-	30-29	-	-	2,44	-	2,44	2,5	6,1	-	1,28	7,38
33-34		-	-	2,39	-	-	2,39	2,5	5,98	-	-	5,98
34-35		33-34 29-34	27-34	3,92	2,39 2,44	43,86	52,61	1,68	88,38	0,37	9,02	97,77
35-36	-	34-35	-	-	52,61	-	52,61	1,68	88,38	-	9,39	97,77
36-37		-	35-36	3,92	-	52,61	56,53	1,66	93,84	7,78	9,39	111,01
37-38	-	36-37	-	-	56,53	-	56,53	1,66	93,84	52,92	17,17	163,93
38-40		-	37-38	2,87	-	56,53	59,4	1,62	96,23	0,26	70,09	166,58
19-18		-	-	2,39	-	-	2,39	2,5	5,98	-	-	5,98
18-24		19-18	-	2,44	2,39	-	4,83	2,5	12,08	0,40	-	12,48
24-23	-	18-24	-	-	4,83	-	4,83	2,5	12,08	-	0,40	12,48
17-22	23,17	-	-	3,12 2,57	-	-	5,69	2,42	13,77	8,11	-	21,88
22-23		-	17-22	2,78	-	5,69	8,47	2,19	18,55	1,4	8,11	28,06
23-31	13, 12	24-23	22-23	5,3 1,80	4,83	8,47	20,4	1,88	38,35	2,23	9,91	50,49
32-31		-	-	2,07	-	-	2,07	2,5	5,18	-	-	5,18
31-39	-	32-31 23-31	-	-	2,07 20,4	-	22,47	1,85	41,57	-	12,14	53,71
39-40	-	31-39	-	-	22,47	-	22,47	1,85	41,57	-	12,14	53,71
40-GNS	-	39-40	38-40	-	22,47	59,4	81,87	1,62	132,63	-	82,49	215,12

Hydraulic calculation and high-altitude design of household networks.

After I have determined the estimated costs, the next stage in the design of the drainage network is its hydraulic calculation and height design. Hydraulic calculation network consists of selecting the diameter and slope of the pipeline in sections so that the speed and filling values ​​in the pipeline comply with the requirements of SNiP 2.04.03-85. High-rise design network consists of calculations necessary when constructing a network profile, as well as to determine the minimum value of the street network. When calculating the hydraulic network, I use Lukin’s tables.

Requirements for hydraulic calculations and height

Designing a household network.

When performing hydraulic calculations I use the following requirements:

1. The entire calculated flow rate of the section goes to its beginning and does not change along its length.

2. The movement in the pipeline in the design section is pressure-free and uniform.

3. The smallest (minimum) diameters and slopes of gravity networks are accepted in accordance with SNiP 2.04.03-85 or table. 5.1.

4. The permissible design filling in pipes when the design flow rate is missed should not exceed the standard one and, in accordance with SNiP 2.04.03-85, is given in table. 5.2.

5. Flow velocities in pipes at a given design flow rate must be no less than the minimum ones, which are given in accordance with SNiP 2.04.03-85 in table.

6. The maximum permissible flow speed for non-metallic pipes is 4 m/s, and for metal pipes – 8 m/s.

Table 5.1

Minimum diameters and slopes

Note: 1. The slopes that can be used for justification are indicated in brackets. 2. In populated areas with a flow rate of up to 300 m 3 /day, the use of pipes with a diameter of 150 mm is allowed. 3. For industrial sewerage, with appropriate justification, the use of pipes with a diameter of less than 150 mm is allowed.

Table 5.2

Maximum fillings and minimum speeds

7. The speed of movement on the section must be no less than the speed on the previous section or the highest speed in the side connections. Only for sections transitioning from steep to calm terrain is a decrease in speed allowed.

8. Pipelines of the same diameter are connected (matched) “according to the water level,” and different ones “according to the shelygs.”

9. The diameters of pipes should increase from section to section; exceptions are allowed when the slope of the area increases sharply.

10. The minimum depth should be taken as the greater of two values: h 1 = h pr – a, m,

h 2 = 0.7 + D, m,

where h pr is the standard soil freezing depth for a given area, adopted according to SNiP 2.01.01-82, m;

a – parameter accepted for pipes with a diameter of up to 500 mm – 0.3 m, for pipes with a larger diameter – 0.5 m;

D – pipe diameter, m.

The standard freezing depth of the Republic of Mordovia is 2.0 m.

h 1 = 2.0 – 0.3 = 1.7;

h2 = 0.7 + 0.2 = 0.9;

The minimum laying depth for this area is 1.7 m.

The average depth of groundwater is taken to be 4.4 m.

12. Areas with flow rates less than 9 - 10 l/s are recommended to be considered “off-design”, while the diameter and slope of the pipe are equal to the minimum, speed and filling are not calculated.

Calculation of household network

In the table in Form 6, I enter the results of the calculation of each gravity section. First, I fill out the columns with the initial data - columns 1, 2, 3, 10 and 11 (expenses - from the last column of form 5, length and elevation of the land - according to the city general plan). Then we carry out hydraulic calculations sequentially for each section in the following order:

Table 5.3

Plot number	Length, m	Ground marks, m
at first	at the end
1-2	10,16
2-3	19,96
3-4	25,9
4-5	32,84
6-7	2,0		162,5
7-8	11,32	162,5
8-9	11,32
9-14	14,19
12-13	4,9	162,5
13-14	7,15
14-15	21,39		161,8
10-15	7,96		161,8
15-16	26,82	161,8	160,2
11-16	2,83	160,3	160,2
16-21	30,1	160,2
21-26	36,82
20-25	8,21	163,5	162,5
28-25	6,36		162,5
25-26	14,57	162,5
26-27	45,82
27-34	82,74
30-29	7,38	162,7
29-34	7,38
33-34	5,98	162,5
34-35	97,77
35-36	97,77
36-37	111,01
37-38	163,93
38-40	166,58
19-18	5,98	163,5	163,3
18-24	12,48	163,3
24-23	12,48		162,4
17-22	21,88	162,5	162,5
22-23	28,06	162,5	162,4
23-31	50,49	162,4	161,4
32-31	5,18	162,3	161,4
31-39	53,71	161,4	160,5
39-40	53,71	160,5
40-GNS	215,12

1. If the section is uphill, then the depth of the pipeline at the beginning of the section h 1 is taken equal to the minimum h min , and the approximate diameter is taken equal to the minimum for the adopted type of network and drainage system (Table 5.1). If a site has adjacent upstream sections, then the initial depth is approximately taken to be equal to the greatest depth at the end of these sections.

2. I calculate the approximate slope of the pipeline:

i o = (h min – h 1 + z 1 – z 2)/l, (5.1)

where z 1 and z 2 are the marks of the ground surface at the beginning and end of the section;

l is the length of the section.

The result may be a negative slope value.

3. I select a pipeline with the required diameter D, filling h/D, flow velocity v and slope i according to the known calculated flow rate. I select pipes according to the tables of A.A. Lukins. I start the selection with the minimum diameter, gradually moving to larger ones. The slope must be no less than the approximate i 0 (and, if the pipe diameter is equal to the minimum, no less than the minimum slope - Table 5.1). The filling should be no more than permissible (Table 5.2). The speed must be, firstly, no less than the minimum (Table 5.2), and secondly, no less than the highest speed in adjacent sections.

If the flow rate in a section is less than 9-10 l/s, then the section can be considered undesigned: I take the diameter and slope to be minimal, but I do not adjust the filling and speed. I fill in columns 4, 5, 6, 7, 8 and 9.

I calculate the fall using the formula: ∆h=i·l, m

where, i – slope,

l – length of the section, m.

The filling in meters is equal to the product of the filling in fractions and the diameter.

4. From all the sections adjacent to the beginning, I select the section with the greatest depth, which will be conjugate. Then I accept the type of coupling (depending on the diameter of the pipes in the current and mating sections). Then I calculate the depths and marks at the beginning of the section, and the following cases are possible:

a) If the conjugation is “by water”, then the water mark at the beginning of the section is equal to the water mark at the end of the conjugate section, i.e. I rewrite the values ​​from column 13 into column 12. Then I calculate the bottom elevation at the beginning of the section, which is equal to the ground elevation at the beginning of the section minus the depth at the beginning of the section and write the result in column 14.

b) If the conjugation is “by shelygs”, then I calculate the bottom mark at the beginning of the section: z d.beg. =z d.resistance +D tr.resistance - D tr.tek.

where, z d.resistance - bottom mark at the end of the adjacent section, m.

D tr.cont. – diameter of the pipe in the adjacent section, m.

D tr.tek. – diameter of the pipe in the current section, m.

I write this value in column 14. Then I calculate the water mark at the beginning of the section, which is equal to the sum of the bottom mark at the beginning of the section z d.beg. and depth at the beginning of the site and write it down in column 12.

c) If the site does not have a junction (i.e. upstream or after the pumping station), then the bottom elevation at the beginning of the site is equal to the difference between the elevation of the ground surface at the beginning of the site and the depth at the beginning of the site. I determine the water mark at the beginning of the section similarly to the previous case, or, if the section is not calculated, I take it equal to the bottom mark, and put dashes in columns 12 and 13.

In the first two cases, the depth at the beginning of the section is determined by the formula: h 1 = z 1 - z 1d.

5. I calculate the depth and marks at the end of the section:

The bottom elevation is equal to the difference between the bottom elevation at the beginning of the section and the fall,

The water mark is equal to the sum of the bottom mark at the end of the section and the filling in meters or the difference in the bottom mark at the beginning of the section and the fall,

The laying depth is equal to the difference in elevations of the water surface and the bottom at the end of the section.

If the laying depth turns out to be greater than the maximum depth for a given type of soil (in my case, the maximum depth is 4.0 m), then at the beginning of the current section I install a regional or local pumping station, the depth at the beginning of the section is taken equal to the minimum, and I repeat the calculation, starting from point 3 (I do not take into account speeds on adjacent sections).

I fill out columns 13, 15 and 17. In column 18 you can write down the type of interface, the interfaced area, the presence of pumping stations, etc.

I present the hydraulic calculation of the gravity sewer network in Form 6.

Based on the results of the hydraulic calculation of the drainage network, I build a longitudinal profile of the main collector of one of the drainage basins. By constructing a longitudinal profile of the main collector we mean drawing its route on a cross-section of the area in sections up to the GNS. I present the longitudinal profile of the main collector in the graphical part. I accept ceramic pipes, since groundwater is aggressive to concrete.

Plot no.	Consumption, l/s	Length, m	Uk-lon	Drop, m	Diameter, mm	Speed, m/s	Filling	Markings, m	Depth	Note
Earth	water	bottom
shares	m	at first	at the end	at first	at the end	at first	at the end	at first	at the end
1-2	10,16		0,005	1,3		0,68	0,49	0,10			158,4	157,1	158,3		1,7
2-3	19,96		0,004	1,32		0,74	0,55	0,14			157,09	155,77	156,95	155,63	3,05	4,37	N.S.
3-4	25,9		0,003	0,39		0,73	0,50	0,15			158,45	158,06	158,3	157,91	1,7	2,09
4-5	32,84		0,003	0,93		0,78	0,58	0,17			158,08	157,15	157,91	156,98	2,09	3,02
6-7	2,0		0,007	1,05		-	-	-		162,5	-	-	161,3	160,25	1,7	2,25
7-8	11,32		0,005	1,45		0,70	0,52	0,10	162,5		162,6	158,9	160,25	158,80	2,25	3,2
8-9	11,32		0,005	0,55		0,70	0,52	0,10			158,9	158,35	158,8	158,25	3,2	3,75	N.S.
9-14	14,19		0,005	1,4		0,74	0,60	0,12			160,42	159,02	160,30	158,9	1,7	4,1	N.S.
12-13	4,9		0,007	1,89		-	-	-	162,5		-	-	160,8	158,91	1,7	4,09	N.S.
13-14	7,15		0,007	0,84		-	-	-			-	-	161,3	160,46	1,7	2,54
14-15	21,39		0,004	1,12		0,75	0,57	0,14		161,8	161,44	160,32	161,3	160,18	1,7	1,62
10-15	7,96		0,007	1,96		-	-	-		161,8	-	-	160,3	158,34	1,7	3,46
15-16	26,82		0,003	0,24		0,75	0,52	0,16	161,8	160,2	158,4	158,16	158,24		3,56	2,2
11-16	2,83		0,007	1,82		-	-	-	160,3	160,2	-	-	158,6	156,78	1,7	3,42
16-21	30,1		0,003	0,45		0,76	0,55	0,17	160,2		156,85	156,4	156,68	156,23	3,52	3,77
21-26	36,82		0,003	1,65		0,76	0,51	0,18			156,36	154,71	156,18	154,53	3,82	5,47	N.S.
20-25	8,21		0,007	2,52		-	-	-	163,5	162,5	-	-	160,8	158,28	1,7	4,22	N.S.
28-25	6,36		0,007	2,59		-	-	-		162,5	-	-	161,3	158,71	1,7	3,79
25-26	14,57		0,004	1,16		0,69	0,46	0,12	162,5		160,92	159,76	160,8	159,64	1,7	0,36
26-27	45,82		0,003	1,08		0,79	0,58	0,20			159,74	158,66	159,54	158,46	0,46	1,54
27-34	82,74		0,002	0,76		0,84	0,60	0,27			158,63	157,87	158,36	157,6	1,64	2,4
30-29	7,38		0,007	2,87		-	-	-	162,7		-	-		158,13	1,7	4,87	N.S.
29-34	7,38		0,007	1,75		-	-	-			-	-	161,3	159,55	1,7	0,45
33-34	5,98		0,007	2,59		-	-	-	162,5		-	-	160,8	158,21	1,7	1,79
34-35	97,77		0,002	0,86		0,87	0,67	0,30			157,9	157,04	157,6	156,74	2,4	3,26
35-36	97,77		0,002	0,5		0,87	0,67	0,30			157,04	156,54	156,74	156,24	3,26	3,76
36-37	111,01		0,002	0,42		0,87	0,63	0,32			156,51	156,09	156,19	155,77	3,81	4,23	N.S.
37-38	163,93		0,002	0,42		0,91	0,71	0,39			158,69	158,27	158,3	157,88	1,7	2,12
38-40	166,58		0,002	0,46		0,91	0,72	0,40			158,28	157,82	157,88	157,42	2,12	2,58
19-18	5,98		0,007	2,94		-	-	-	163,5	163,3	-	-	161,8	158,86	1,7	4,44	N.S.
18-24	12,48		0,005	1,3		0,71	0,55	0,11	163,3		161,71	160,41	161,6	160,3	1,7	2,7
24-23	12,48		0,005	0,9		0,71	0,55	0,11		162,4	160,41	159,51	160,3	159,4	2,7
17-22	21,88		0,004	0,48		0,75	0,58	0,15	162,5	162,5	160,95	160,47	160,8	160,32	1,7	2,18
22-23	28,06		0,003	0,69		0,75	0,53	0,16	162,5	162,4	160,43	159,74	160,27	159,58	2,23	2,82
23-31	50,49		0,003	0,9		0,82	0,62	0,22	162,4	161,4	159,65	158,75	159,43	158,53	2,97	2,87
32-31	5,18		0,007	2,17		-	-	-	162,3	161,4	-	-	160,6	158,43	1,7	2,97
31-39	53,71		0,003	0,9		0,83	0,65	0,23	161,4	160,5	158,61	157,71	158,38	157,48	3,02	3,02
39-40	53,71		0,003	0,36		0,83	0,65	0,23	160,5		157,71	157,35	157,48	157,12	3,02	2,88
40-gns	215,12		0,002	0,1		0,91	0,60	0,42			157,19	157,09	156,77	156,67	3,23	3,33

Here insert the transverse profile of the river, which is on the graph paper

Calculation of the siphon.

When hydraulically calculating and designing a siphon, the following conditions must be observed:

Number of working lines – at least two;

The diameter of steel pipes is at least 150 mm;

The route of the siphon must be perpendicular to the fairway;

The side branches must have an angle of inclination to the horizon α - no more than 20º;

The laying depth of the underwater part of the siphon h is not less than 0.5 m, and within the fairway - not less than 1 m;

The clear distance between drainage lines b should be 0.7 - 1.5 m;

The speed in the pipes must be, firstly, not less than 1 m/s, and secondly, not less than the speed in the supply manifold (V in. ≥ V in.);

The water mark in the inlet chamber is taken to be the water mark in the deepest collector approaching the siphon;

The water mark in the outlet chamber is lower than the water mark in the inlet chamber by the amount of pressure loss in the siphon, i.e. z out = zin. - ∆h.

The procedure for designing and hydraulic calculation of the siphon:

1. On graph paper, I draw a profile of the river at the site where the siphon is laid on the same horizontal and vertical scales. I outline the branches of the siphon and determine its length L.

2. I determine the estimated flow rate in the siphon in the same way as the flow rates in the design areas (i.e., I take it from form 5).

3. I accept the design speed in the siphon V d. and the number of working lines.

4. Using Shevelev’s tables, I select the diameter of the pipes according to the speed and flow rate in one pipe, equal to the calculated flow rate divided by the number of working lines; I find the pressure loss in pipes per unit length.

5. I calculate the pressure loss in the siphon as the sum:

where - coefficient of local resistance at the input = 0.563;

Velocity at the outlet of the siphon, m/s;

- the sum of pressure losses at all turns in the siphon;

Rotation angle, degrees;

Coefficient of local resistance in the turning elbow (Table 6.1)

Table 6.1

Local resistance coefficients in the elbow (with a diameter of up to 400 mm.)

6. I check the possibility of passing the entire calculated flow through one line during emergency operation of the siphon: at the previously specified diameter, find the speed and pressure loss in the siphon ∆h emergency.

7. The following inequality must be observed: h 1 ≥ ∆h emergency. - ∆h,

where h 1 is the distance from the earth’s surface to the water in the inlet chamber

If this ratio is not met, then increase the diameter of the lines until the condition is met. Find the flow speed at this diameter and normal operating mode of the siphon. If the speed is less than 1 m/s, then one of the lines is accepted as a backup.

8. The water level in the outlet chamber of the siphon is calculated.

In our case, the siphon is 83 m long with an estimated flow rate of 33.13 l/s. One collector (4-5) with a diameter of 300 mm and a flow speed of 0.78 m/s is suitable for the siphon; the speed in the pipeline behind the siphon is 0.84 m/s. The duker has two branches with an angle of 10º in the lower and ascending branches. The water level in the entrance chamber is 157.15 m, the distance from the surface of the earth to the water is 2.85 m.

We accept 2 working siphon lines. Using Shevelev’s table, we accept at a flow rate of 16.565 l/s steel pipes with a diameter of 150 mm, water speed 0.84 m/s, pressure loss per 1 m – 0.0088 m.

We calculate the pressure loss:

Along the length: ∆h 1 =0.0088*83=0.7304 m.

At the entrance: ∆h 2 =0.563*(0.84) 2 /19.61=0.020 m.

At the output: ∆h 3 =(0.84 -0.84) 2 /19.61=0 m.

At 4 turns: ∆h 4 =4*(10/90)*0.126*(0.84) 2 /19.61=0.002 m.

General: ∆h=0.7304 +0.020 +0 +0.002 =0.7524 m.

We check the operation of the siphon in emergency mode: at a flow rate of 33.13 l/s and a pipe diameter of 150 mm. We find the speed to be 1.68 m/s and the unit pressure loss to be 0.033. We recalculate the pressure loss:

Length: ∆h 1 =0.033*83=2.739 m.

At the entrance: ∆h 2 =0.563*(1.68) 2 /19.61=0.081 m.

At the output: ∆h 3 = (0.84-1.68) 2 /19.61 = 0.036 m.

At 4 turns: ∆h 4 =4*(10/90)*0.126*(1.68) 2 /19.61=0.008 m.

General: ∆h emergency = 2.739 +0.081 +0.036 +0.008 =2.864 m.

We check the condition: 2.85 ≥ (2.864-0.7524 =2.1116 m). The condition is met. I check the pipeline for flow leakage under normal operating conditions: at a flow rate of 33.13 m/s and a diameter of 150 mm. the speed will be 1.68 m/s. Since the resulting speed is more than 1 m/s, I accept both lines as working.

We calculate the water mark at the outlet of the siphon:

z out = zin. - ∆h= 157.15 - 2.864=154.29 m.

Conclusion.

While carrying out the course project, we calculated the city’s drainage network, which is presented in the calculation and explanatory note, based on the initial data, and based on the calculations we made a graphical part.

In this course project, a drainage network of a settlement in the Republic of Mordovia with a total population of 35,351 people was designed.

We chose a semi-separate drainage system for this region, since the water flow rate of 95% supply is 2.21 m 3 /s, which is less than 5 m 3 /s. We also chose a centralized drainage system for this settlement, since the population is less than 500 thousand people. and a crossed scheme, because the laying of the main collector is planned along the lower edge of the facility’s territory, along the water channel.

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SEWERAGE - EXTERNAL NETWORKS AND STRUCTURES - SNiP 2-04-03-85 (approved by Decree of the USSR State Construction Committee dated 21-05-85 71) (edited from 20-05-86)... Relevant in 2018

Specific costs, unevenness coefficients and estimated wastewater flow rates

2.1. When designing sewerage systems in populated areas, the calculated specific daily average (per year) drainage of domestic wastewater from residential buildings should be taken equal to the calculated specific daily average (per year) water consumption according to SNiP 2.04.02-84 without taking into account water consumption for watering territories and green spaces.

2.2. Specific drainage for determining the estimated wastewater flows from individual residential and public buildings, if it is necessary to take into account concentrated costs, should be taken in accordance with SNiP 2.04.01-85.

2.7. The calculated maximum and minimum wastewater flows should be determined as the product of the average daily (per year) wastewater flows determined according to clause 2.5 by the general unevenness coefficients given in Table 2.

table 2

General coefficient of unevenness of wastewater inflow	Average wastewater flow, l/s
	5	10	20	50	100	300	500	1000	5000 or more
Maximum K_gen.max	2,5	2,1	1,9	1,7	1,6	1,55	1,5	1,47	1,44
Minimum K_gen.min	0,38	0,45	0,5	0,55	0,59	0,62	0,66	0,69	0,71

3. For intermediate values ​​of the average wastewater flow, the overall unevenness coefficients should be determined by interpolation.

2.8. The estimated costs of industrial wastewater from industrial enterprises should be taken as follows:

For external collectors of the enterprise that receive wastewater from workshops - at maximum hourly flow rates;

For on-site and off-site collectors of the enterprise - according to a combined hourly schedule;

for the off-site collector of a group of enterprises - according to a combined hourly schedule, taking into account the time of flow of wastewater through the collector.

2.9. When developing the schemes listed in clause 1.1, the specific average daily (per year) water disposal can be taken according to Table 3.

The volume of wastewater from industrial and agricultural enterprises should be determined on the basis of consolidated standards or existing analogue projects.

Table 3

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. 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 from Table 3.

2.10. 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 clauses 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 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

q_ad = 0.15L square root (m_d),

(1)

Where L is the total length of pipelines to the calculated structure (pipeline site), km;

m_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.

4 Calculation of treatment facilities

4.1 Determination of the flow of wastewater entering treatment plants and the coefficient of unevenness

We calculate the throughput capacity of treatment facilities using the formulas of SNiP 2.04.03-85, taking into account the characteristics of the incoming wastewater:

the average daily wastewater inflow is 4000 m 3 /day, the maximum daily wastewater inflow is 4500 m 3 /day, the hourly unevenness coefficient is 1.9.

The average daily flow rate is 4000 m 3 /day. Then, the average hourly consumption

where Q average daily consumption,

The maximum hourly consumption will be

Q max =q avg K h.max (6)

where K h max is the maximum hourly unevenness coefficient accepted according to the standards

K h. max =1.3·1.8=2.34

Maximum coefficient of daily unevenness

By day max =1.1.

Then the maximum daily consumption

Q day.max =4000·1.1=4400 m 3 /day.

Maximum hourly consumption

.

4.2 Determination of wastewater flows from a populated area and local industry (cheese factory)

The design capacity of the cheese plant is 210 tons/day. The daily wastewater flow from the cheese plant is determined by its actual capacity equal to 150 tons of milk processing per day.

The standard wastewater consumption is 4.6 m 3 per 1 ton of processed milk. Then the daily consumption of wastewater from the cheese plant is

Q daily comb =150·4.6=690 m 3 /day.

The concentration of wastewater contaminants (BOD total combined) for the cheese plant is according to 2400 mg/l. The amount of pollutants entering the wastewater treatment plant from the cheese plant will be

BOD full combination = 2400 690 = 1656 g/day.

Wastewater flow from a populated area can be determined as the difference between the maximum daily flow rate entering the wastewater treatment plant and the daily wastewater flow from the cheese plant

Q days max – Q daily comb =4400-690=3710 m 3 /day.

According to the standards, the amount of pollution from one person BOD total = 75 g/day. The number of inhabitants in the settlement is 16,000 people.

Total amount of pollution

BOD total mountains =75·16000=1200 g/day.

Let us determine the amount of contamination in a mixture of domestic and industrial wastewater

BOD full cm. =(1656+1200)/4400=649 mg/l.

4.3 Calculation of sand traps and sand pads

Sand traps are designed to retain mineral impurities (mainly sand) contained in wastewater, in order to avoid their precipitation in settling tanks together with organic impurities, which could create significant difficulties in removing sludge from settling tanks and its further dewatering.

For our runoff, we will calculate a sand trap with circular movement of water, shown in Figure 1.

1 – hydraulic elevator; 2 – pipeline for removing floating impurities

Figure 1 - sand trap with circular movement of water

The movement of water occurs along a ring tray. The fallen sand enters the cone part through the cracks, from where it is periodically pumped out by a hydraulic elevator.

The average daily flow of wastewater entering the treatment plant is 4000 m 3 /day.

Secondary flow rate q avg.sec, m 3 /s, is determined by the formula

q avg.sec =, (7)

q avg.sec = (m 3 /s)

The overall coefficient of unevenness of water disposal is equal to 1.73, therefore, the maximum calculated flow rate of wastewater entering the treatment plant is equal to

q max .s = 0.046·1.73 = 0.08 m 3 / s = 288 m 3 / h.

We determine the length of the sand trap using formula 17

Ls= (8)

where Ks is the coefficient accepted according to table 27, Ks=1.7;

Hs is the estimated depth of the sand trap, m;

Vs is the speed of movement of wastewater, m/s, taken according to table 28;

Uo is the hydraulic sand size, mm/s, taken depending on the required diameter of the retained sand particles.

Ls = m

The estimated area of ​​the open cross-section of the annular tray of one sand trap will be found using formula 2.14

, (9)

where qmax. c - maximum design wastewater flow rate equal to 0.08 m 3 /s;

V is the average speed of water movement equal to 0.3;

n – number of branches.

m 2

We determine the estimated productivity of one sand trap

Introduction

1. Calculation part

1.2. Determining the volume of tanks of water towers and clean water reservoirs

1.3. Construction of a piezometric line. Selection of pumps 2 lifts

2. Technological part

2.1. Water quality and basic methods of its purification

2.2. Selection of technological scheme for water purification

2.3. Reagent facilities

2.4. Water disinfection

2.5. Selection of technological equipment for a water treatment plant

Conclusion

Application

Bibliography

Introduction

The urban economy is a set of enterprises engaged in the production and sale of housing and communal products and services.

A municipal sector is a set of enterprises that sell the same type of products and services.

Centralized water supply is one of the important sectors of the urban economy, which has a number of features and performs its functions in the life of the urban economy.

Centralized water supply is a branch of urban management that provides water consumers with water in the required quantities, the required quality and under the required pressure.

A set of engineering structures that perform water supply tasks is called a water supply system (pipeline).

Centralized water supply provides the population with water, which must be safe against infections, harmless in chemical composition and with good organoleptic qualities.

This industry has a number of technological features:

1. Constancy (the unchanged state of technological stages, regardless of the size of the technology);

2. Continuity (implementation of technological stages in a strict repeating sequence).

But like many sectors of the urban economy, water supply has its own problems and disadvantages. This includes insufficient funding for the maintenance, timely overhaul and current repairs of equipment, for the acquisition and operation of modern technologies, hence the constant failures in the operation of equipment and technology. As a result, this affects the quality of water supplied to homes, its chemical and physical composition.

1. CALCULATION PART

1.1. Norms and regimes of water consumption

Estimated water consumption is determined taking into account the number of inhabitants of a populated area and water consumption standards.

The norm for household and drinking water consumption in populated areas is the amount of water in liters consumed per day by one resident for household and drinking needs. The rate of water consumption depends on the degree of improvement of buildings and climatic conditions.

Table 1

Water consumption standards

Smaller values ​​refer to areas with a cold climate, and larger values ​​​​to areas with a warm climate.

Throughout the year and during the day, water for household and drinking purposes is consumed unevenly (in summer it is consumed more than in winter; in the daytime - more than at night).

The estimated (average for the year) daily water consumption for household and drinking needs in a populated area is determined by the formula

Qday m = ql Nl/1000, m3/day;

Qday m = 300*150000/1000 = 45000 m3/day.

Where ql – specific water consumption;

Nzh – estimated number of inhabitants.

Estimated water consumption per day of the highest and lowest water consumption, m3/day,

Qday max = Kday max* Qday m;

Qday min = Kday min* Qday m.

The coefficient of daily unevenness of water consumption Kday should be taken equal to

Kday max = 1.1 – 1.3

Kday min = 0.7 – 0.9

Larger values ​​of Kday max are taken for cities with large populations, smaller values ​​for cities with small populations. For Kday min it’s the other way around.

Qday max = 1.3*45000 = 58500 m3/day;

Qday min = 0.7*45000 = 31500 m3/day.

Estimated hourly water consumption, m3/h,

qch max = Kch max * Qday max/24

qch min = Kch min * Qday min/24

The coefficient of hourly unevenness of water consumption is determined from the expressions

Kch max = amax * bmax

Kch min = amin * bmin

Where a is a coefficient that takes into account the degree of improvement of buildings: amax = 1.2-1.4; amin = 0.4-0.6 (smaller values ​​for amax and larger values ​​for amin are taken for a higher degree of improvement of buildings); b is a coefficient that takes into account the number of residents in a locality.

Kch max = 1.2*1.1 = 1.32

Kch min = 0.6*0.7 = 0.42

qh max = 1.32*58500/24 ​​= 3217.5 m3/h

qh min = 0.42*31500/24 ​​= 551.25 m3/h

Water consumption for fire fighting.

Water is used sporadically to extinguish fires - during fires. Water consumption for external fire extinguishing (per fire) and the number of simultaneous fires in a populated area are taken according to a table that takes into account water consumption for external fire extinguishing in accordance with the number of residents in the populated area.

At the same time, water consumption for internal fire extinguishing is calculated at the rate of two jets of 2.5 l/s per design fire.

The estimated duration of fire extinguishing is assumed to be 3 hours.

Then the supply of water for fire extinguishing

Wп =nп (qп+2.5*2)*3*3600/1000, m3

Where nп is the estimated number of fires; qп – rate of water consumption for one design fire, l/s.

In our case nп = 3; qп = 40 l/s.

Wп = 3 (40+2.5*2)*3*3600/1000 = 1458 m3

Hourly consumption for fire extinguishing

Qp.ch. = Wп/3 = 1458/3 = 486 m3/h

Based on the calculated coefficient of hourly unevenness Kch max = 1.32, we set a probable schedule for the distribution of daily expenses by hour of the day.

According to the table of distribution of daily household and drinking expenses by hour of the day at different coefficients of hourly unevenness for populated areas for Kch max = 1.32, we construct a schedule of daily water consumption and combine with this schedule the schedules of water supply by pumps 1 and 2 lifts.

1.2 Determination of the volume of tanks of water towers and clean water reservoirs

The capacity of the water tower tank can be determined using combined schedules of water consumption and operation of the 2nd lift pumping station. The calculation results are shown in Table 2, which reflects the regulating role of the water tower tank. So, in the period from 22 to 5 a.m., there is a shortage of water not supplied by the pumping station 2 rises, in the amount of 0.1 to 0.8% of the daily consumption every hour will be consumed from the tank; in the period from 5 to 8 hours and from 10 to 19 hours, water will flow into the tank in the amount of 0.2 to 0.7% of the daily flow.