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Original article UDC 628.218
THE PARAMETERS JUSTIFICATION OF NEW AND RECONSTRUCTED SEWAGE SYSTEMS UNDER THE CONDITIONS OF UNCERTAIN PERSPECTIVE WATER CONSUMPTION AND
DISCHARGE OF EFFLUENTS
© Ngoc Minh Pham1, R.V. Chupin2, V.R. Chupin3, E.S. Melekhov4
1Vinh University,
Vietnam, Nghe An, Vinh, str. Le Duan, 182. 23,4Irkutsk National Research Technical University, 83, Lermontov St., Irkutsk, 664074, Russian Federation.
Abstract. Purpose. Due to the energy and resource saving policies implemented in our country, the specific water consumption by the population has decreased significantly (liters per person per day). It is difficult to predict if this indicator will continue to decrease. There is some uncertainty in the choice of specific values of water consumption by the population when developing promising schemes of water supply and sanitation systems for a period of 15 years or more. The paper proposes a methodology for justifying the specific values of water consumption and drainage by periods and stages of sewerage systems development. Method. This method is based on the theory of fuzzy sets, interval mathematics and decision theory. The essence of the proposed methodology is as follows. The possible load interval is divided into several specific values. For each value of the loads, the parameters of the perspective scheme for sewerage systems development are justified. Thus, based on the obtained options, a risk matrix is formed. Result. As a preferred option, a variant with minimal total risks is proposed. After that the construction of the first stage is carried out. Loads and their possible intervals for subsequent construction phases are specified and the second phase construction option is justified, etc. Conclutions. This technique allows to take into account the uncertainty of information about the behavior of the water disposal system in the future.
Keywords: perspective schemes, sewerage systems development, loads presentation, fuzzy sets
For citation: Ngoc Minh Pham, Chupin R.V., Chupin V.R., Melekhov E.S. The parameters justification of new and reconstructed sewage systems under the conditions of uncertain perspective water consumption and discharge of effluents. Izvestiya vuzov. Investitsii. Stroitel'stvo. Nedvizhimost' [Proceedings of Universities. Investments. Construction. Real estate], 2017, vol. 7, no. 2, pp. 49-61. (In Russian)
Introduction
In the era of developed socialism, the growth of water consumption per 1 person was considered as the indicator of the well-being of the population. Therefore, this indicator increased and in the 90s of last century reached the highest value of 400 l/person per day on average in the Russian Federation. In some regions it was 1000 l/person a day or more. On the basis of these indicators, design standards were formed and they were aimed at outstripping growth rates of specific water consumption. For pre-design work, these rates were 500-600 l/person per day (SNIP 2.04.02-84), according to which by 1990 the rate should be 550 l/person per day, and by 2000 - 600 l/person per day. Unfortunately, well-being of the population has not increased significantly, but wastefulness of water resources, expressed both in terms of money and in volumetric indicators, became
significant. At the same time, the huge volumes of discharge of non-treated wastewater have made our reservoirs environmentally hazardous and polluted. Only the transition to market relations stimulated the beginning of energy and resource saving in our country. This process has been going on for several decades. In the latest editions of SNIP (SP 31.13330.2012, SP 32.1330.2012), the specific norm of water consumption is designated at the level of 220-280 l/person per day. To date, the actual consumption in Russia on the average in cities is approaching the number of 150-170 l/person. per day. And the water saving limit has not yet reached its lowest value (Fig. 1). It still remains large enough because of the dilapidated networks of water leakage and run-off, which are estimated at 10-20 % of the total volume of water supplied to the city and discharged drains.
1
Ngoc Minh Pham, Lecturer in Department of Civil Engineering, e-mail: minhrow@gmail.com
2Roman V. Chupin, Candidate of technical sciences, senior researcher, Institute of Architecture and Construction, e-mail: ch-r-v@mail.ru
3Viktor R. Chupin, Doctor of technical sciences, professor, Director of the Institute of Architecture and Construction, e-mail: chupinvr@istu.edu
4Evgeny S. Melekhov, Candidate of technical sciences, Associate Professor, Department of Urban Construction and Economy, e-mail: melechov@istu.edu
Q (1/person per day)
1990 2000 2010 2020 2030 1
Fig. 1. Reducing the values of specific water consumption in Irkutsk
In general, energy and resource-saving policies have many positive aspects. In particular, the costs for pumping water and sewage have decreased, and there are reserves for connecting new subscribers to the network. The pressure in the network has decreased, and as a result, the accident rate has decreased. At the same time, the speed of water movement and effluents decreased (in comparison with the design values). And in the climate of Siberia, some water pipes in which the water velocity became less than the normative ones, were frozen. In sewerage systems, the amount of deposits has increased and, as a result, the number of failures and the time of their elimination (cleaning) increased, the treatment facilities and pumping stations began to operate in irrational and energy-consuming modes of operation.
Obviously, there is a problem of bringing water supply and water disposal systems to the required technological, hydraulic, environmental and reliability parameters arises. This task is included in the overall problem of reconstruction and development of engineering networks and facilities in the context of energy and resource-saving policies, the use of new technologies and materials. At the same time, we do not know what water consumption will be in 15-30 years. Whether it will decrease, or increase, and at what period it happens, it is difficult to predict in advance. Obviously, this process needs to be evaluated and predicted. On the other hand, today it is required to take to the construction or reconstruction the variant of networks and structures that would take into account the subsequent stages of development and take into account possible values of specific water consumption.
The current level of urbanization in the Russian Federation, and indeed in all countries of the world, is characterized by the fact that the number of people living in large cities is increasing due to migration processes. Migration of
people occurs from populated areas to small towns, and from small towns to medium-sized, medium-to-large cities [1]. In the future, small towns will turn into populated areas, some medium-sized cities will turn into small ones. A significant increase in the population (20 million or more people) will be observed in Moscow. Already, the developers of general plans and programs for the development of integrated engineering infrastructure in some cities were faced with the fact that the specific indicators of consumption of communal services are decreasing, while the population is decreasing, and engineering communications have considerable wear (60-80 %). For rapidly growing cities, a decrease in specific water consumption will not lead to a decrease in water consumption and diversion, and, consequently, an increase in the capacity and throughput of networks is required, including due to the re-laying and parallel laying, or the construction of deep-laid sewers. For "fading" cities, it will be necessary not only to re-lay smaller diameters pipelines (channel or nonchannel), but also to change the scheme of water supply and sanitation. The complex tasks of reconstruction (removal of moral and physical deterioration) and the conservation of networks and structures with their decommissioning become obvious. The solution of these problems requires the improvement of the existing methodology for the design and justification of perspective schemes of water supply and sewerage systems. These are the issues that are the subject of research in this publication.
Material and methods of research
According to SP 32.13330.2012 gravity drainage systems are designed as a rule in one thread (cl. 6.1.1), calculated with the prospective planning for the maximum possible flow rate and with the greatest filling. In this case, the slopes of the collectors are taken in the interval: K/d <I <0.15, where d - diameter of the collector in mm, K is the correction factor, takes a value depend-
ing on the size of the collector diameter, for example: K = 1 for d<300 mm; K = 3 for d> 1000 mm. The smallest slopes of pipelines for all sewerage systems are adopted: d150 mm -0.008; d200 mm - 0.007. The minimum speed of movement of sewage depends on the diameter of the collector and has a range: 0.7-1.5 m/s. The maximum speeds have restrictions, respectively for domestic and rainwater drainage: 8 m/s and 10 m/s. Filling (the ratio of the depth of runoff to the value of the diameter of the collector) is taken in the range: 0.3-0.8. At filling 0.8 it is considered that the collector operates as a full cross section. At the initial stage of the development of sewerage networks, the flow rates of the runoffs are assumed to be minimally permissible, and with the connection of new subscribers, the filling and speeds increase. For example, a collector with d 500 mm, with a slope of 0.019, can pass 0.45 m3/s in a non-pressure mode with a filling of 0.78 and a speed of 2.8 m/s. The minimum flow rate will be 0.3 and a velocity of 1.84 m/s at 0.085 m3/s. Thus, this manifold can work in gravity flow in the range of flow rates from 0.085-0.45 m3/s. At a flow rate of 0.5 m3/s or more, the network will overflow. At a flow rate of less than 0.085 m/s it will be silted up. In either case, its reconstruction is required.
(iaA 1 ■
220
For triangular, trapezoidal and rectangular forms, fuzzy sets can be written in terms of membership functions as follows:
Qa = {220| 0; 250| 1; 280| 0};
Qb= {220| 0; 240| 1; 260| 1; 280| 0};
Qc = {219.9| 0; 220| 1; 280| 1; 280.19| 0}.
According to the submitted records, water charges up to 220 l/person per day inclusive have a degree of membership of 0, as well as expenditures of more than 280 l/person per day. For expenses from 220 to 250 liters, the degree of membership increases from 0 to 1, and for expenditures from 250 to 280 decreases from 1 to 0. Obviously, each form of the fuzzy set representation will have its own time interval. For example, experts have determined the interval of specific water consumption for the perspec-
It is well known that water consumption and water disposal have a probabilistic and cyclical character, and a certain trend as well [2]. With sufficient accuracy, this process can be described by an autocorrelation function [3, 4]. In this case, the trend can have a cyclic character in the form of growth or decrease in specific water consumption. The problems of modeling, optimization, and decision-making on sewerage systems were discussed in the works of foreign authors [15-26]. Some of the approaches proposed by them are presented in this article. Stochastic models are well recommended for solving problems of operational and short-term control of regimes in water supply and sewerage systems [5-7]. As for the tasks of long-term planning and design (for a period of 15-30 years), these models give a significant error. In this case, the most simple and effective are models and methods based on odd sets [8] and interval mathematics [9]. The specific norm of water consumption by experts in the form of values of 220 + 280 l/person per day can be expressed in a fuzzy set using the membership function ^a (x): X [0,1], in the form of a linearly triangular and trapezoidal shape (see Fig. 2).
tive of 10 years at a rate of 220-280 liters per person based on the fact that in the current year the water consumption was close to 250 liters per person per day. We are not confident that in subsequent periods it will increase or decrease. Therefore, for the near future (for example, up to 3-5 years), the membership function can be considered a triangular shape (Fig. 2, a); From 5-10 years in the form of a trapezoid (Fig. 2, b); From 10-15 years in the form of a rectangle (Fig. 2, c). Assuming that due to energy and resource saving measures, the specific water consumption will decrease and reach a rational (minimum) value, for example 50 l/person per day, fuzzy sets for three time intervals can be represented as the following sequence (Fig. 3).
250 280 q (L/person 220 240 250 260 280 220 280
a) per day) b) c)
Fig. 2. Fuzzy representation of perspective water consumption:
a - triangular; b - trapezoidal; c - interval (rectangular) shape
Ца 1 -
150 Q
50
150 Q
50 150 Q 50 100
a) b) c)
Fig. 3. Indistinct representation of specific water consumption in conditions of its reduction
When comparing the options for reconstruction of networks and structures, the values of the membership function can be taken into account in a form of coefficients of appreciation, which are defined as follows:
Ku=1+(1- MaW). (1)
In this case, the rationale for the reconstruction of the water disposal system will be as follows:
- the minimum and maximum possible load values for existing and new subscribers are assigned;
- the membership functions for each subscriber are defined;
- the possible interval of loads is divided in equal parts and for each load the numerical value of the membership function is determined;
- for each load value, optimization problems are solved and the cost of the reconstruction option is determined;
- taking into account the coefficients of appreciation, risks are calculated from the adoption of various values of estimated water consumption and water disposal.
For the criterion for assessing the design options for wastewater disposal systems, the total reduced costs are taken to one year for the construction and operation of all network elements, including the cost of pumping electricity for transported environment.
3 = (E + f) • K + c33r,
where 3 - reduced costs; K - investment in the network; E - efficiency coefficient of investment, which in the conditions of a market economy is identified with bank interest; fc - the share of
allocations for depreciation, repair and maintenance of the network; a, - the unit cost of electricity; Эг - annual electricity demand. To make the given costs more specific, the information given in the enlarged norms of construction prices was used in the work: NDC 81-02-142012. "Water supply and sewerage networks".
The boundary values of the calculated water consumption can be assigned not only according to the requirements of the SP, but also by experts, or be determined on the basis of variants of the forecast (optimistic and pessimistic) population size, volume of housing construction, etc. [10, 11].
Results and its discussion
For example, we will justify the parameters of the collector length of 1 km with a slope of 0.019, according to which the drains will be diverted from the newly constructed area by 100 thousand people. In the current year, the specific water consumption was 250 l/person per day. According to the SP, the calculated values of specific water consumption are taken in the interval 220-280 l/person per day. Therefore, for this example, the interval of estimated costs will be as follows: 0.173-0.324 m3/s. Given the actual water consumption, the membership function has a triangular shape (Fig. 2, a). To build this function, we divide the possible load interval into the following values:
Q=(0.173|0.01; 0.21110.5; 0.249|1.0; 0.287|0.5; 0.324|0.01)
For each load value, we define the diameters, cost, and values of the membership function (Table 1).
Table 1
Selection of the design variant based on the membership function (Fig. 2, a)
Reduced costs, million rub. Member- Coeff. of Reduced
Flow, M3/s Theoretical diameter, mm ship functions appreciation. cost stalk into account Option of preference
Ма(х) Ku Ku
0.173 270 39.4 0.01 1.99 78.4 4
0.211 290 39.9 0.5 1.5 59.9 2
0.249 310 40.3 1.0 1.0 40.3 1
0.287 320 40.7 0.5 1.5 61.1 3
0.324 340 41.1 0.01 1.99 81.8 5
A variant with a design flow rate of 0.249 m3/s is preferred. However, before making a final decision, we will evaluate all possible risks. For this it is proposed to use the "risk matrix", which for the example is presented in table 2. In this matrix, the first calculated row and the first column are the values of the estimated explored load. On the diagonal are 0, which means the coincidence of the accepted load value with those that will be after the project is implemented (100 % coincidence option). The values to the right of the diagonal indicate the risk values from the fact that the actual load value after the project implementation will be greater than their values chosen before the project implementation. For example, a flow rate of 0.173 m3/s was chosen and a collector d 270 mm was built, and at the time of completion, the flow rate was 0.211 m3/s, those on 0.027 m3/s more. Therefore, either a rearrangement or expansion is required, but a parallel laying of a new collector d170 mm with a present value of 36.9 million rubles is cheaper (this is a risk). If the flow is 0.324 m3/s, the risk will already be 39.2 million rubles.
To the left of the diagonal in the matrix are the risk values associated with overestima-
If we take into account the coefficients of appreciation, in accordance with the adopted membership function (Fig. 2, a), then the option of the design flow with the lowest total risk will also be 0.324 m3/s (Table 3). If the specific water consumption is certain to decrease within the time period under investigation, then it is possible to construct the membership function by tak-
tion of parameters and consequently with excessive capital investments. For example, a flow rate of 0.211 m3/s was chosen, and after the project was realized 0.173 m3/s. For a flow rate of 0.211 m3/s, the design diameter of the collector is 290 mm and its present value is 39.9 million rubles (Table 1). For a flow rate of 0.173 m3/s, the design diameter is 270 mm and the present value is 39.4 million rubles. Consequently, the amount of risk is calculated at 0.5 million rubles (Table 2). The last column of the "risk matrix" presents the total risks for each variant of the estimated flow. The preferred option with a minimum risk position will be the option with a flow rate of 0.324 m3/s. The last row of the "risk matrix" presents the values of the maximum risks from the adoption of those or other decisions. The last element of this row corresponds to the minimum value of the maximum risks (Savage criterion [12]). This criterion corresponds to a flow rate of 0.171 m3/s. However, the total risk for this load is 152.6 million rubles. Consequently, we accept the option with a design flow rate of 0.324 m3/s.
Table 2
ing a fuzzy representation in the form of a rectangular triangle (Fig. 3, c):
Qa= (0.173|1; 0.21110.75; 0.249|0.5; 0.287|0.25; 0.324|0).
In this case, the "Risk Matrix" will have the values presented in table 4, which implies that the flow rate can be taken as the design value of 0.324 m3/s.
Table 3
"Risk matrix", making allowance for the values of the membership function
3 Flow, m /s 0.173 0.211 0.249 0.287 0.324 I , mill. rub.
0.173 0.0 73.5 75.4 76.9 78.0 303.7
0.211 0.7 0.0 55.4 56.9 57.9 170.8
0.249 0.9 0.4 0.0 36.9 37.9 76.1
0.287 1.9 1.2 0.6 0.0 55.3 58.9
0.324 3.1 2.2 1.4 0.7 0.0 7.4
Min max 3.1 73.5 75.4 76.9 78.0 3.1
"Risk matrix" except the values of the membership function
3 Flow, m /s 0.173 0.211 0.249 0.287 0.324 I , mill. rub.
0.173 0 36.9 37.9 38.6 39.2 152.6
0.211 0.5 0 36.9 37.9 38.6 113.9
0.249 0.9 0.4 0 36.9 37.9 76.1
0.287 1.2 0.8 0.4 0 36.9 39.3
0.324 1.6 1.1 0.7 0.3 0 3.7
Min max 1.6 36.9 37.9 38.6 39.2 1.6
Table 4
"Risk matrix", making allowance for the values of the membership function_
3 Flow, m /s 0.173 0.211 0.249 0.287 0.324 I . mill. rub.
0.173 0.0 36.9 37.9 38.6 39.2 152.6
0.211 0.6 0.0 46.1 47.4 48.3 142.3
0.249 1.3 0.6 0.0 55.4 56.8 114.1
0.287 2.2 1.4 0.6 0.0 64.5 68.7
0.324 3.1 2.2 1.4 0.7 0.0 7.4
Min max 3.1 36.9 37.9 38.6 39.2 3.1
Let's consider one more test example of the construction of a sewerage system from three districts to three stages (Fig. 4). Combining the intervals of node loads, we get the intervals of possible loads for the collectors and con-
struction stages (Table 5). Based on the calculated values presented in Table. 6, payment matrices are constructed taking into account triangular, trapezoidal and rectangular membership functions (Tables 7-9).
0.173-0.324 nrVs 0.15-0.3 nrVs 0:l-0:3 m3/s
/
1 km 1 km
-О--«
l = 0.019 i = 0,019
1 km ^Z. 1 km ~,
in* (fin 1 ^—
/
1 = 0.019
Fig. 4. Construction of a sewage collector in three stages
Calculated values of collector parameters
Table 5
Flow, m3/s Diameter, m The reduced costs, million rub.
Section 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
0-I 0.423 0.548 0.674 0.799 0.924 0.4 0.45 0.5 0.5 0.55 41.8 42.7 43.4 44.1 44.7
I-II 0.25 0.338 0.425 0.513 0.6 0.35 0.4 0.4 0.45 0.45 40.4 41.2 41.8 42.5 43.0
II-III 0.1 0.150 0.200 0.250 0.3 0.25 0.3 0.3 0.35 0.35 38.4 39.2 39.8 40.4 40.8
- £=120.6 123.0 125.1 126.9 128.5
Table 6
The reduced costs making allowance for Ku_
The membership function Ма (х) Coefficientofappreciation, Ku The reduced coststalk into account Ku, million rub
0.01 0.5 1 0.5 0.01 1.99 1.5 1 1.5 1.99 83.2 64.0 43.4 66.1 88.9
0.01 1 1 1 0.01 1.99 1 1 1 1.99 80.3 41.2 41.8 42.5 85.6
1 1 1 1 1 1 1 1 1 1 38.4 39.2 39.8 40.4 40.8
X=201.9 144.3 125.1 148.9 215.3
Table 7
"Risk matrix" except the values of the membership function_
3 Flow, m /s 0.423 0.548 0.674 0.799 0.924 I , mill. rub.
0.423 0 114.2 118.2 121.1 122.8 476.4
0.548 2.4 0.0 114.2 118.2 121.1 356.0
0.674 4.5 2.1 0.0 114.2 118.2 239.0
0.799 6.3 3.9 1.8 0.0 114.2 126.2
0.924 7.9 5.5 3.4 1.6 0 18.4
Min max 7.9 114.2 118.2 121.1 122.8 7.9
Table 8
"Risk matrix", making allowance for the values of the triangular membership function_
3 Flow, m /s 0.423 0.548 0.674 0.799 0.924 I , mill. rub.
0.423 0.0 227.3 235.3 241.0 244.4 948.0
0.548 3.7 0.0 171.3 177.4 181.7 534.0
0.674 4.5 2.1 0.0 114.2 118.2 239.0
0.799 9.5 5.8 2.7 0.0 171.3 189.3
0.924 15.8 10.9 6.8 3.2 0.0 36.7
Min max 15.8 227.3 235.3 241.0 244.4 15.8
Table 9
"Risk matrix", making allowance for the values of the membership function in the form of a right _triangle_
3 Flow, m /s 0.423 0.548 0.674 0.799 0.924 I , mill. rub.
0.423 0.0 114.2 118.2 121.1 122.8 476.4
0.548 3.1 0.0 142.8 147.8 151.4 445.0
0.674 6.8 3.1 0.0 171.3 177.4 358.5
0.799 11.0 6.8 3.2 0.0 199.9 220.8
0.924 15.8 10.9 6.8 3.2 0.0 36.9
Min max 15.8 114.2 142.8 171.3 199.9 15.8
In all cases, the most preferable is the option with the maximum loads. It should be noted that in the test examples with five intervals of the breakdown of possible load, five variants of their combination are considered. However, such combinations are much larger. For their analysis and search, it is proposed to use the dynamic programming tool. The scheme of such variants is shown in Fig. 5. According to this scheme, the computational process begins with the design of the third stage of construction. The sewerage network and facilities are calculated for drainage flow from 0.1 m3/s to 0.3 m3/s. Load
КОС /
О-О—
3
of the second stage from 0.25 to 0.6 m /s, provided that the third stage is designed first for a flow rate of 0.1 m3/s, then for a flow rate of 0.15
33
m /s, ..., 0.3 m /s. The best option for these reduced costs for each load value from 0.25 to 0.60 should be kept in mind. Further, the conditionally optimal solution for the first stage is increased. Of all the expenditure values 0.423 ... 0.924, using the risk matrix, the preferred option is chosen and the corresponding combination of loads for each construction stage is restored in reverse.
Fig. 5. Accumulation of conditionally optimal solutions in the direction from the last stage of
construction to the first one
It is not difficult to see that for gravity sewerage systems under the conditions of uncertainty of wastewater loads, the option with their maximum values is preferable. This is explained by the fact that the collector, designed for maximum loads, will drain the minimum waste water, but if the expenditure is higher than calculated, an expensive reconstruction will be required (even in the form of a parallel laying of
a new collector). What cannot be said about the pressure sewage system. Here, from the viewpoint of minimizing risks, the minimum values of load should be assumed. Consider a pressure sewage system consisting of a pumping station and two pressure pipelines 10 000 m in length. The difference in geodetic marks is 55 m. The range of possible loads is 50-150 l/s. The calculi_
Table 10
"Risk matrix", making allowance for the values of the trapezoidal membership function_
Q, l/s Theoretical diameter, mm The reduced estimated costs, million rubles The membership function Ма(х) Coeff. of appreciation, Ku The reduced estimated costs, Ku Option of prefe-rence
50 2d500 905.5 0.01 1.99 1802.0 3
75 2d590 940.8 0.5 1.5 1411.2 2
100 2d650 968.6 1.0 1.0 968.7 1
125 2d700 989.9 0.5 1.5 1484.9 4
150 2d750 1011.1 0.01 1.99 2012.2 5
Table 11
"Risk matrix" except the values of the membership function_
3 Flow, m /s 50 75 100 125 150 I , mill. rub.
50 0 1.6 2.2 2.9 3.6 10.4
75 35.3 0 2.1 2.7 3.3 43.5
100 63.1 27.8 0 2.6 3.2 96.9
125 84.3 49.1 21.2 0 3.2 157.9
150 105.6 70.3 42.5 21.2 0 239.7
Min max 105.6 70.3 42.5 21.2 3.6 3.6
Table 12
"Risk matrix", making allowance for the values of the membership function_
3 Flow, m /s 50 75 100 125 150 I , mill. rub.
50 0 3.2 4.4 5.7 7.2 20.7
75 52.9 0 3.2 4.1 5.0 65.2
100 63.1 27.8 0 2.6 3.2 96.9
125 126.5 73.6 31.8 0 4.8 236.9
150 210.1 140.0 84.6 42.3 0 477.0
Min max 210.1 140.0 84.6 42.3 7.2 7.2
Table 13
"Risk matrix", making allowance for the values of the membership function in the form of a _rectangular triangle_
3 Flow, m /s 50 75 100 125 150 I , mill. rub.
50 0 1.6 2.2 2.9 3.6 10.4
75 44.1 0 2.7 3.4 4.2 54.4
100 94.7 41.7 0 4.01 4.9 145.3
125 147.6 85.9 37.2 0 5.6 276.4
150 211.2 140.7 85.0 42.5 0 479.5
Min max 211.2 140.7 85.0 42.5 5.6 5.6
The rationale for the estimated discharge of the sewage collector from Fr. Baikal to Irkutsk. In 2013 the institute of JSC "Mos-vodokanalNIIproekt" developed a perspective scheme of water supply and water disposal of Irkutsk and Irkutsk region for the period 2015, 2020 and 2025. In terms of wastewater disposal, the most important task of protecting lake Baikal was to remove wastewater from the developing Listvyanka settlement located on the shore of
the lake and from the settlements of the "Baikal" tract to the treatment plant in Irkutsk. It was suggested to develop a sewage collector along "Baikal" tract, the length of 72 km with the device 8 SPS with pressure pipelines in two threads of 31 km in length and with gravity collectors, the length of 41 km. The schematic diagram is shown in Fig. 6. The calculation scheme is shown in Fig. 7. The results of the calculations are shown in tables 15-19.
Fig. 6. Sewer collector from Baikal to the sewage treatment plants of Irkutsk
Table 14
The estimated discharge of the sewage collector
Settlements Node Prediction flow, l/s Priority of commissioning Possible intervals of flow, l/s
Listvyanka 40 14.66 3 10-50
Bolshayareka 42 12.12 3 10-40
Burdakovka 44 10.63 2 10-20
Burduguz 45 6.41 2 5-10
Elovui 46 51.81 1 40-60
Molodzornui 59 109.34 1 100-120
Pervomaisky-Pivovarikha 59-0 95.03 1 85-105
- - I 300 - I 260-405
Table 15
Estimated loads for sewerage sections_
Listvyanka - Bolshaya Reka 10-50 10 20 30 40 50
BolshayaReka - Burdakovka 20-90 20 37.5 55 72.5 90
Burdakovka - Burduguz 30-110 30 50 70 90 110
Burduguz - Elovui 35-120 35 56.25 77.5 98.75 120
Elovui - Molodzornui 75-180 75 101.25 127.5 153.75 180
Molodzornui - Pivovariha 175-300 175 206.25 237.5 268.75 300
Pervomaisky - KOC 260-405 260 296.25 332.5 368.75 405
Table 16
Calculated parameters of the sewer collector_
Section Flow, l/s Diameter, mm Cost, million rubles 3 = (ß+L)-(KHC +К1Р) + сэЭг +э„ +энс
40-0 10 20 30 40 50 2d300 2d300 2d300 2d300 2d300 477.6 478.0 478.4 478.9 479.6
0-41 10 20 30 40 50 d200 d200 d200 d200 d200 87.2 87.2 87.2 87.2 87.2
41-0 10 20 30 40 50 2d200 2d200 2d200 2d200 2d200 78.1 78.5 78.9 79.5 80.2
0-42 10 20 30 40 50 d200 d200 d200 d200 d200 37.1 37.1 37.1 37. 37.1
42-0 20 37.5 55 72.5 90 2d350 2d350 2d350 2d350 2d350 265.2 265.0 265.4 265.9 266.8
0-43 20 37.5 55 72.5 90 d200 d200 d200 d200 d200 27.8 27.8 27.8 27.8 27.8
43-0 20 37.5 55 72.5 90 2d350 2d350 2d350 2d350 2d350 358.9 359.4 359.9 360.5 361.2
0-44 20 37.5 55 72.5 90 d200 d200 d200 d200 d200 34.8 34.8 34.8 34.8 34.8
44-0 30 50 70 90 110 2d400 2d400 2d400 2d400 2d400 433.8 434.3 434.9 435.7 436.5
0-45 30 50 70 90 110 d200 d200 d200 d200 d200 37.2 37.2 37.2 37.2 37.2
45-0 35 56.25 77.5 98.75 120 2d400 2d400 2d400 2d400 2d400 295.1 295.7 296.4 297.1 297.9
0-0 35 56.25 77.5 98.75 120 d200 d250 d250 d300 d300 86.7 89.0 89.1 91.4 91.4
0-0 35 56.25 77.5 98.75 120 d200 d200 d200 d250 d250 56.5 56.5 56.5 58.1 58.1
0-46 35 56.25 77.5 98.75 120 d200 d250 d300 d300 d350 124.2 127.6 130.9 130.9 134.3
46-59 75 101.25 127.5 153.75 180 2d400 2d400 2d400 2d400 2d400 75.0 75.6 76.2 76.8 77.5
59-0 175 206.25 237.5 268.75 300 2d600 2d600 2d600 2d600 2d600 142.1 142.4 142.8 143.2 143.6
0-24а 260 296.25 332.5 368.75 405 d400 d400 d450 d450 d450 326.2 326.2 334.0 334.0 334.0
I 2943.8 2952.6 2967.9 2976.5 2985.4
Table 17
"Risk matrix" except the values of the membership function_
3 Flow, m /s 0.26 0.2962 0.332 0.3687 0.405 I , mill. rub.
0.26 0 769.0 791.4 808.8 824.1 3193.4
0.2962 8.9 0 769.3 792.1 810.0 2380.2
0.332 24.1 15.3 0 769.7 792.9 1602.0
0.3687 32.7 23.9 8.6 0 770.2 835.4
0.405 41.6 32.7 17.5 8.9 0 100.7
Min max 41.6 769.0 791.4 808.8 824.1 41.6
Table 18
"Risk matrix", with allowance for the values of the membership function_
3 Flow, m /s 0.26 0.2962 0.332 0.3687 0.405 I , mill. rub.
0.26 0 1530.3 1574.9 1609.6 1640.0 6354.9
0.2962 13.3 0 1153.9 1188.1 1215.0 3570.4
0.332 24.1 15.3 0 769.6 792.9 1602.0
0.3687 49.1 35.8 12.9 0 1155.2 1253.1
0.405 82.9 65.2 34.8 17.6 0 200.5
Min max 82.9 1530.3 1574.9 1609.6 1640.0 82.9
Table 19
"Risk matrix", with allowance for the values of the membership function in the form of a right _triangle_
3 Flow, m /s 0.26 0.2962 0.332 0.3687 0.405 I , mill. rub.
0.26 0 769.0 791.4 808.8 824.1 3193.4
0.2962 11.1 0 961.6 990.1 1012.5 2975.3
0.332 36.2 22.9 0 1154.5 1189.4 2403.1
0.3687 57.3 41.8 15.0 0 1347.8 1461.9
0.405 83.2 65.5 34.9 17.7 0 201.5
Min max 83.2 769.0 961.6 1154.5 1347.8 83.2
As can be seen from the table 17-19, the preferred option is the one with the highest flow rate of 0.405 m3/s. This option is assumed as the main one. At the same time, after the construction of the first stage with the actualization of the perspective scheme for the development of water supply and sewerage systems, it is recommended to make similar calculations for the subsequent construction stages, taking into account the actually achieved costs and determine the parameters for the construction of the next stage of the construction of the water disposal system. The proposed method is implemented in the TRACE-VR software package,
which is successfully used to substantiate promising schemes for the development of water disposal systems [13, 14].
Conclusions
A new methodology for justifying options for development, analysis and optimization of the parameters of water disposal systems with a risk assessment of the decisions taken is proposed. This technique allows to take into account the uncertainty of information about the behavior of the water disposal system in the future and embodies the principle of "making a decision with minimal lead time".
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Contribution
Ngoc Minh Pham, Chupin R.V., Chupin V.R., Melekhov E.S. have equal author's rights. Ngoc Minh Pham bears the responsibility for plagiarism.
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Conflict of interests
The authors declare no conflict of interests regarding the publication of this article.
The article was received 03 May 2017
