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Оригинальная статья / Original article УДК 628,218
DOI: http://dx.doi.org/10.21285/2227-2917-2018-2-94-107
INDICATIVE AND ADAPTIVE MANAGEMENT OF WASTEWATER SYSTEM IMPROVEMENT
© R.V. Chupina, Pham Ngoc Minhb, E.A. Gorkovc, M.V. Morozd
a,c,dIrkutsk National Research Technical University, 83, Lermontov St., Irkutsk, 664074, Russian Federation b Vinh University, 182, Le Duan St., Vinh, Vietnam
ABSTRACT. AIM. The transition to a market economy both in the Russian Federation and the Republic of Vietnam has determined the implementation of a new technology for managing urban engineering systems. This technology involves two stages. The first stage consists in the development of water supply and sanitation system schemes. The second stage involves the implementation of these schemes on the basis of investment programmes in the housing and utilities sector. METHODS. Investment programmes imply financial support for the development and reconstruction of drainage systems by means of the investment component in the housing and utilities rate tariff, payment for the newly-introduced facilities and targeted funding on the part of state and municipal projects, loans and credits. Under such an approach, investments and their effective allocation to various stages and periods of the drainage system development become of particular significance. This raises new issues and challenges associated with the rational allocation of investments in the construction of new and reconstruction of existing facilities and structures of drainage systems. An effective approach is a technique based on the preliminary development of the redundant project schemes of drainage systems, as well as the solution of optimization structural and parametric problems based on these schemes. RESULTS AND DISCUSSION. On the basis of the developed models and methods for the assessment of the structure and parameters of drainage systems, we propose a technique for the creation and optimization of drainage systems under the conditions of unpredictable specific water consumption, limited resources of investment programmes in the housing and utilities sector, ambiguous indicators against which indicative and adaptive management is performed. CONCLUSIONS. The proposed technique can be successfully used in the context of market economy, which is increasingly penetrating the sphere of housing and communal services. Keywords: optimal development management, sewerage systems, redundant scheme, quantitative indicators of reliability, seismic stability, environmental safety, limited investments
Article info. Received February 27, 2018; accepted for publication March 12, 2018; available online June 26, 2018.
For citation. Chupin R.V., Pham Ngoc Minh, Gorkov E.A., Moroz M.V. Indicative and adaptive management of wastewater system improvement. Izvestiya vuzov. Investitsii. Stroitel'stvo. Nedvizhimost' = Proceedings of Universities. Investment. Construction. Real estate. 2018, vol. 8, no. 2, pp. 94-107. (In Russian). DOI: 10.21285/2227-2917-2018-2-94-107.
эЧупин Роман Викторович, кандидат технических наук, старший научный сотрудник Института архитектуры, строительства и дизайна, e-mail: [email protected]
Roman V. Chupin, Candidate of technical sciences, senior researcher, Institute of Architecture, Construction and Design, e-mail: [email protected]
ьФам Нгок Минь, преподаватель кафедры промышленного и гражданского строительства, e-mail: [email protected]
Pham Ngoc Minh, Lecturer, Department of Civil Engineering, e-mail: [email protected]
Торьков Евгений Алексеевич, аспирант кафедры городского строительства и хозяйства,
e-mail: [email protected]
Evgeny A. Gorkov, Post-graduate student, Department of Urban Construction and Economy, e-mail: [email protected]
^ороз Мария Викторовна, старший преподаватель, аспирант кафедры инженерных коммуникаций и систем жизнеобеспечения, e-mail: [email protected]
Maria V. Moroz, Senior lecturer, Postgraduate of the Department of Engineering Communications and Life Support Systems, e-mail: [email protected]
ИНДИКАТИВНОЕ И АДАПТИВНОЕ УПРАВЛЕНИЕ РАЗВИТИЕМ СИСТЕМЫ ВОДООТВЕДЕНИЯ
Р.В. Чупин, Н.М. Фам, Е.А. Горьков, М.В. Мороз
Иркутский национальный исследовательский технический университет, 664074, Российская Федерация, г. Иркутск, ул. Лермонтова, 83. Винь Университет,
Республика Вьетнам, г. Винь, ул. Ле Зуан, 182.
РЕЗЮМЕ. ЦЕЛЬ. Переход к рыночным отношениям определил новую как для Российской Федерации, так и для Республики Вьетнам технологию управления развитием городских инженерных систем. Данную технологию можно представить в виде двух этапов. Первый - разработка схем развития систем водоснабжения и водоотведения, второй - реализация этих схем на основе инвестиционных программ предприятий коммунального комплекса. МЕТОДЫ. В инвестиционных программах формируется финансовое обеспечение развития и реконструкции систем водоотведения за счет инвестиционной составляющей в тарифе, платы за подключение для вновь вводимых в строй объектов капитального строительства и целевого финансирования по отдельным государственным и муниципальным программам, займам и кредитам. При таком подходе определяющими становятся инвестиции и их ограниченность по этапам и периодам развития системы водоотведения. В связи с этим возникают новые проблемы и задачи, связанные с рациональным распределением инвестиций в строительство новых и реконструкцию существующих объектов и сооружений систем водоотведения. Эффективным подходом является методика, основанная на предварительном построении избыточных проектных схем систем водоотведения и решении на их основе оптимизационных структурных и параметрических задач. РЕЗУЛЬТАТЫ И ИХ ОБСУЖДЕНИЕ. В представленном исследовании на основе разработанных моделей и методов для обоснования структуры и параметров систем водоотведения предлагается методика формирования и оптимизации вариантов развития системы водоотведения в условиях неопределенности удельного водопотребления и ограниченных инвестиций, формирующихся за счет инвестиционных программ предприятий коммунального комплекса, в условиях неопределенности показателей, по которым осуществляется индикативное и адаптивное управление. ВЫВОДЫ. Данная методика соответствует рыночным отношениям, которые все глубже проникают в эту жизненно важную отрасль - жилищно-коммунальное хозяйство.
Ключевые слова: оптимальное управление развитием, система водоотведения, избыточная схема, ограниченные инвестиции, количественные показатели надежности, сейсмостойкости, экологической безопасности.
Информация о статье. Дата поступления 27 февраля 2018 г.; дата принятия к печати 12 марта 2018 г.; дата онлайн-размещения 26 июня 2018 г.
Формат цитирования. Чупин Р.В., Фам Н.М., Горьков Е.А., Мороз М.В. Индикативное и адаптивное управление развитием системы водоотведения // Известия вузов. Инвестиции. Строительство. Недвижимость. 2018. Т. 8. № 2. С. 94-107. DOI: 10.21285/2227-2917-2018-2-94-107
Introduction
Many branches of the national economy of our country have already moved into market relations and are developing successfully what can not be said about communal life support systems, for which this process turned out to be long and complicated. Aware of this situation, the Government acted as a regulator in the market of public utilities and proposed new mechanisms for the restoration and development of communal infrastructure. The essence of these mechanisms is set out in 210 federal law "About the basics of tariff
regulation of utilities" and is specified in more than 40 by-laws and guidelines. All problems of maintenance, operation and development of engineering infrastructure are proposed to be solved at the expense of the main tariffs, the investment component in the tariff and the tariff for connection to engineering networks for newly created real estate objects. The investment program and calculation of connection fees have become the most important documents in the formation of tariffs at both the municipal and regional levels. The basis for the development of investment pro-
grams is the program of integrated development of engineering infrastructure for the future. In turn, a comprehensive program for the development of engineering infrastructure should be formed on the basis of master plans for the development of cities and territories. At the same time, on the way to the transition from the entire construction industry and communal systems to market relations, the general plans and technologies for their formation turned out to be the most conservative because of the difficulties that have arisen in forecasting and realizing housing construction. The directive approach that existed before proved to be untenable. For many cities, the figures on housing construction in the master plans, were not achievable. The new housing code assumes that housing construction will be mainly implemented at the expense of the population's funds, including the variety of schemes for attracting them.
As already noted, the volume of construction must correspond to the purchasing power of the population. Thus, the welfare of its inhabitants becomes the determining factor in the development of urban engineering infrastructure. The more it is available, the more opportunities are available to improve the quality of the provided utilities. The reasoning is quite trivial, but it requires clarity in the formation of a scheme for implementing this policy. Deviations in housing development, the acquisition and purchase of housing, the collection of utility fees and connection fees can bring this policy to naught. It so happened in many cities, after the development and implementation of the first investment programs of utilities. It was required to refine and improve the methodology for managing the development of engineering infrastructure. These improvements and experience of municipalities and utilities are summarized in order No.204 of 0.05.2011 of the Ministry of Regional Development of the Russian Federation "About the development of programs for the integrated
development of communal infrastructure systems of municipalities" in the form of methodological guidelines that emphasize not only the formation of the program itself, but also the possibility of its implementation. The term indicative management has appeared. Indicators or targets become the basis for their monitoring.
Indicators are divided into technical, economic, environmental, social, energy and other indicators. For water supply and sanitation systems, important indicators are: specific water consumption per capita per day; leakage of water per one km of the pipeline; energy consumption per cubic meter of water supplied or consumed; indicators of reliability, safety, seismic stability, etc.
Indicator management is the development and implementation of activities aimed at improving or achieving certain values of these indicators. This raises the question of predicting the attainability of the level of indicators. For example, such important indicator as specific water consumption. In the second half of the 20th century, this indicator increased sharply and reached 410 liters per person per day. In 2017 this indicator has already approached the figure of 200 liters per person per day. However, at the same time, another problem arose, the problem of the conformity of capacities, parameters of structures, pipeline diameters to actual loads. Already, many of the structures were half underloaded, although the operating costs remain unchanged. Not to mention possible violations of the technological process, an increase in tariffs is unavoidable [1]. To prevent such negative consequences, it is possible to manage the following indicators: specific losses in pipelines; filling in gravity collectors; Efficiency of pumping units and pumping stations; specific electricity consumption for lifting and transporting water and pumping waste water. Activities that can ensure the optimality of these indicators will be as follows: redistribution of transported water, sewage
between loaded and underloaded structures and pipelines; pipeline laying for lower productivity or their complete conservation; reconstruction of pumping stations or their closure, etc. An important indicator is the specific electricity consumption per 1 m3 of drinking water, or per 1 m3 of treated sewage, which is directed not only to energy saving and efficiency of pump units, but also to reduce the cost of communal products. The activities that are required to be carried out in this case are of a complex nature and refer both to technical means and to the organization of their operation [2-5].
Measures aimed at improving these indicators are as follows: reduction in the intensity of failures due to the relocation and rehabilitation of dilapidated and emergency pipelines and structures; introduction of an operational system for detection, localization and elimination of emergency situations; structural redundancy of networks and structures, including justification and transition to closed-loop sewerage systems.
Thus, the transition to market relations in the sphere of housing and utilities has determined the following stages of managing the development of urban engineering infrastructure:
1. State and municipal regulation of investments in the development and reconstruction of engineering systems is carried out. This regulation is reduced to the following items:
- for the management of the development of engineering systems, a forecast is made for the years of wages, profitability and population;
- assessment of the existing utility tariffs is performed, the level of payment for utility services, depending on the profitability of the population, a forecast is set for this indicator;
- limit indices of growth of utility tariffs are established and their forecast is carried out for the years of development of engineering systems;
- the volume of financial security is calculated at the expense of possible investment components in tariffs;
- based on the profitability of the population, a forecast is made for the volume of housing construction and social and cultural facilities;
- the market value of primary and secondary housing is estimated and the forecast of possible tariffs for connection of real estate to engineering networks is made;
- calculate the amount of financial security due to the connection fee.
As a result, for each year of development of engineering systems, a possible financial security plan is formed at the expense of the investment component in the tariff and connection fees.
2. Indicative management of the development of engineering systems is carried out, which is as follows:
- all indicators are formed, ranked and grouped according to their importance;
- an indicative assessment of the existing state of engineering systems;
- taking into account the existing state, a step-by-step forecast of achievability of each indicator is made;
- activities for each indicator or their group that meet financial accessibility are assigned and that allows the indicator or their group to be brought to the forecast values.
It should be noted that if at some stage of management there are no activities that would allow to achieve the required values of the indicator, the indicator is corrected. But if there is such an event, but its financial needs exceed investment opportunities, additional investments are sought from budgets of various levels, federal or regional programs, or a loan is taken in the bank. Such measures include construction of new water intakes, water supply and sewage treatment facilities.
3. Selection of measures for development and reconstruction of engineering systems is carried out.
Under the action, it is necessary to understand ready-made projects and technologies for their implementation. As before, the design should be multi-variate. For example, the problem of providing water and drainage for new housing projects can be solved by attaching them to existing engineering systems, and can be solved in a decentralized way by building separate water intakes or treatment facilities. But at the same time this or that project should be considered not only through the prism of economic criteria, but also from the position of all other indicators. Projects, as well as earlier, can be short-term and long-term. Everything depends on their financial support. Obviously, projects to restore dead pipelines and facilities are expensive and therefore will be permanent and long-term. All activities that will be considered for individual stages and for the entire period of development should be divided into three groups.
The first group. These are measures aimed at improving the quality of the provided public services, i.e. those activities that will form the investment component in the tariff:
- increase of reliability, safety and regime controllability of networks and structures;
- bringing the quality of drinking water and wastewater treatment to modern standards and requirements for the protection of water bodies;
- development of intelligent control systems for regimes and maintenance of the required hydraulic parameters in water supply and sewage systems.
The second group. These are activities aimed at developing and satisfying new consumers with communal services, i.e. those activities that will form tariffs for connection:
- the construction of new networks and structures that join the existing system or form a new, local water supply or sewage system;
- reconstruction of existing systems for water and wastewater flow for new consumers.
The third group. These are especially important and capital-intensive measures, which are difficult to implement due to the growth of tariffs, and which can form the basis for the formation of other federal and regional environmental, socio-economic programs:
- construction of new water intakes, water supply and treatment facilities, large pumping stations;
- the creation and development of a storm sewerage system, the construction of local and centralized facilities for cleaning surface runoff.
It should be noted that in justifying the parameters of new and reconstructed pipeline systems and structures, one should not proceed from the norms of water consumption and discharge of effluents, which are incorporated in SP, but from their actual and forecast values.
4. Monitoring of implementation of measures and achievability of indicators is carried out, which should be permanent and annual. The assessment should be carried out not only in terms of the achievability of the projected indicators, but of the information on the basis of which those or projects were adopted. With the passage of time, the uncertainty of information is removed and this should be expressed in correcting the decisions taken. Organizationally, the monitoring and management of indicators is entrusted to the municipal authorities, which form a plan for the development of the city's engineering infrastructure, it is monitored and adjusted, and if necessary, revised target indicators.
5. Minimization of risks in managing the development of water supply and sanitation systems. Risks of nonfulfillment of activities and achievement of planned indicators may arise due to:
- excess of inflation over the estimated, low wage growth, a sharp rise
in the cost of materials, construction and installation works, etc.;
- failure to complete the plan for the commissioning of capital construction projects;
- failure to fulfill the obligations of the developer in connection with the connection fee;
- not timely implementation of planned activities, etc.
Activities that reduce risks can be as follows:
- formation of insurance funds and attraction of borrowed funds;
- creation of a flexible system to form indicators and activities, as well as ensuring the possibility of reducing or increasing utility tariffs.
Thus, the process of managing the development of engineering systems becomes permanent, continuous, adaptive and financially secure.
The future is for "Reasonable cities", the development strategy of which supposes the creation of a single city-wide information space, which is the basis for a balanced management and development of all components of the city's subsystems. The availability of such an information system will allow to react promptly to changes in the economic, social and environmental situation in the city and to adjust activities for the development of water supply and sanitation systems. For the promptness of management and the formation of measures, a system for modeling water supply and sanitation systems and a set of programs for optimizing the decisions to be made are necessary. [6-13]
The process of managing the development of sewerage systems should be permanent, continuous, adaptive and financially secure. Nevertheless, this process has a legislative basis (the "Law on Water Supply") and is determined by the time of implementation of the prospective scheme of water supply and sanitation (not less than 10 years). Consistency and continuity of management are determined by the stage-by-stage formation of financial support for the im-
plementation of the scheme on the basis of investment programs of utilities, which are approved for a period of at least 3 years. At the same time, the development management process becomes financially secure and at the same time financially limited. Adaptability, expressed in the removal of uncertainty of parameters and operating modes of the system in the future conditions of its operation, is realized through the actualization of the schemes of development of water supply and sewage systems. The principle of "make a decision with minimal lead time" becomes the main one in this sense.
Taking into account the above-mentioned arguments, the following technology is proposed for justifying the parameters of perspective schemes of water supply and sewage systems [5].
Step 1. Determine the time interval for the implementation of water supply and sewerage systems.
Step 2. Based on the sequence of input of capital construction objects and the duration of investment programs, the stages of the implementation of the water supply and sewerage systems are determined.
Step 3. The forecast of technical and economic parameters is carried out and the possible intervals of water consumption and discharge of effluents are assigned for each stage of the implementation of the water supply and sewerage systems.
Step 4. The investment in the construction of each stage of the scheme is assessed on the basis of connection fees and other funds, including dedicated financing, loans and bank lending.
Step 5. Under the conditions of fixed investment values, uncertainty of water consumption and other economic indicators, options for the development of a sewerage system for all stages of its construction and implementation are analyzed.
Step 6. The preferred development option is chosen and the first stage is being constructed.
Step 7. As the first phase of construction is being implemented, economic information, values and intervals of possible loads of water disposal are specified.
Step 8. Taking into account the constructed first stage and taking into account updated information for subsequent construction stages, possible options for further development of water supply and wastewater systems are again analyzed and a decision is made on the construction of the second stage, etc.
In the existing design practice, the comparison of options for the development of sewerage systems is made by the criterion of the minimum of the given estimated costs. However, this criterion takes into account operational costs less, which in recent years often exceeded a one-time investment of 2030 times. It is obvious that in justifying the project of reconstruction and devel-
When constructing redundant schemes, deliberately non-optimal solutions can be avoided and it is possible to generate a set of permissible variants of the structure and parameters of the water disposal systems that differ from each other by the given costs. In the same way, it is possible to designate in advance in any given areas possible ways of their reconstruction (parallel lay-
opment of sewerage systems, the costs of the entire life cycle of the system should be taken into account [2]. However, this criterion in the field of water supply and sewerage systems has not yet acquired a legislative basis, and therefore the comparison of options is based on the discounted present cost criterion.
Methods
In doing so, an effective approach is a technique based on the preliminary construction of redundant design schemes for sewerage systems and the solution of optimization of structural and parametric problems is based on them. Redundant scheme can be formed by imposing in advance the designers worked out alternative options for laying sewers, reconstruction and development of sewerage systems. For example, the designers outlined two options for tracing the sewerage system, which are shown in figure 1a, b. These two options can be replaced by one graph, shown in figure 1c, for which there will already be 8 options to trace the sewerage system.
2
ing, re-laying, laying of a new collector, arrangement of pumping stations, etc.). To find the best option, it is suggested to go from the redundant scheme to the transport network (figure 1, d). When constructing a transport network, all nodes-wastewater collection points are close to a common node-stream inputs, and all nodes-discharges of sewage, or possible sewage treatment facilities (for
area
area 2
area 4
STP 1
О-
STP .
b
STP 1\
T
Redundant scheme c
/ STP 2
STP 1
STP 2 STP 1
'STP
T
Transport network
Optimal solution
Fig. 1. Formation of the redundant and transport network to find the best option for laying
the collectors of the sewerage system
a
e
example, STP-sewage treatment plant 1 and STP 2 in figure 1, c), are close to a common node of the flow output from the transport network (figure 1, d).
The carrying capacity of the branches of the transport network, which simulate the operation of existing sewers, is subject to bilateral restrictions. The first lower limit is assigned from the condition of unencumbered speeds, and the second upper limit is assigned based on the inadmissibility of gravity sewers in the pressure regime. The cost of a unit of flow is determined on the basis of enlarged norms of cost data on investment and operating costs. From a mathematical point of view, the problem is formulated as follows:
X Ci • K
i=l
A • x = œ , (2)
общ ,i • xi ^ min , (1)
< X < !
(3)
at =i
where Cj is the value of the flow, xi is the required flow on the branch of the redundant or transport network, A -the matrix of contiguity of the nodes and sections of the transport network, qp -the vector of average seconds of flow to the sewerage system, e,, e, - lower and
upper flow restrictions, Ko6w, - overall maximum coefficient of uneven sewage movement through pipelines and sewers. The upper limit on the flows of fictitious branches corresponds to the calculated values of the discharge of effluents from the wastewater collection points and the productivity of STP. For new sections of the network, no flow restrictions are imposed.
If the amount of allocated investments in the construction of new and reconstruction of existing networks and structures is known, then the following restriction is added:
X Ci • K
• x < с
общ ,i i —
(4)
Where C - allocated investments for the construction and reconstruction of the sewerage system. When solving
problem (1)-(4), the algorithm of searching the maximum flow of the minimum cost is used [3]. As a result, the allocated investments are optimally distributed in the construction of new and reconstruction of existing sewerage system facilities.
At the same time, the number of new consumers and their loads are determined, from which it is possible to build a sewerage system and divert wastewater from the allocated investments. As a result of the optimization, the route and parameters of the new sections of the network are determined, the options to reconstruct the existing sewers (open method, or laying the pipeline directly in the ground, or laying a parallel pipeline), the location and productivity of the treatment facilities (figure1, e)
At present practically in all cities of the Russian Federation there is a significant decrease in the specific water consumption.
For example, for the city of Irkutsk over the past 17 years it has decreased from 300 to 198 liters per person per day. What will it be by the end of the implementation of the approved scheme of water supply and sewerage system (by 2035).
We can only assume that it will decrease and reach a limit of 100 l/person per day, or return to the previous values. Figure 2 shows the possible intervals and trajectories of changes in the values of specific water consumption by stages of development of the water disposal system. For the first stage of construction, the possible range of specific loads will be (130-220 liters/person per day), for the second stage (110-250 liters per person per day), for third (100-300 liters per person per day).
It should be assumed that there will not be an abrupt change in the specific loads. Therefore, based on the achieved values of specific water consumption, using the theory of fuzzy
i=i
sets, it is possible for each time interval to construct their membership functions.
The membership function (from 0 to 1) in this case can be treated as trust, or distrust, to the numerical values of the specific loads in the studied intervals. For the first, second and third queue, these functions can be repre-
sented respectively in the form of triangular, trapezoidal and rectangular forms (see figure 3, a, b, c). When optimizing the parameters of the sewerage system, the values of these functions serve as a preference and are used as weight functions.
(liter/person A per day) 300
2000
2017
2020
2025
2030
2035
Fig. 2. Possible intervals for the change in the specific water consumption for the period of the implementation of the sewerage scheme
130 190 220 q (1/person 110 150 per day)
a) b)
210 250
100
300
170 180 200 q (1/person 150 170 200 250 165 180 200
per day)
d) e) f)
Fig. 3. Membership functions for different time steps in the implementation of the sewerage
scheme
For each construction queue, the intervals of possible loads are divided into n values. As a result, n options for the development of the sewerage system are formed. For each option, the justification (optimization by criterion (1)) of the parameters of the sewerage system is made for all (in this case three) construction queues. In this case, the option for which the estimated investment in the construction of the first stage exceeds the possible funds generated in investment programs, is ex-
cluded from consideration. For example, for a developing sewerage system consisting of 24 existing, 145 new sections and 104 nodes of a redundant scheme (figure 4), a load breakdown was made and four variants of the development of the sewerage system were obtained (Table 1). For each load value, the problem (1)-(4) is solved and the optimal variants of the scheme of the sewerage system are obtained, which are shown in figures 5-8.
Table 1
Options for the development of a sewerage system in three stages
.Option IQ (l/s) Qi (l/s) Qii (l/s) Qiii (l/s) Reduced costs, million rub.
1 286,4 75,2 95,5 115,7 55,095
2 421,42 92,56 136 192,86 81,512
3 556,5 110 176,5 270 106,037
4 691,5 127,3 217 347,2 128,331
T----+----T----+
I 1 I 1
, A-->--4 I A-->--4
t—^
I 1
f--t—f
4^-4--4
--Ч--+--+--+--+--4
• •
|—f-^-f +—f i 4-->--4 i 4- - -f- -4
! 1 ! ----i----4-----i-----4---
Existing First queue Second queue
# # - Wastewater collection point A - Wastewater weil
• Г--+--Т I - —4
1 I
±-----4
Third queue
Fig. 4. Existing option and redundant scheme of a new sewerage system, the implementation
of which is planned in three stages
Fig. 5. Optimal option of the sewerage system at a design How load of 286.4 liters per second
The results and the discussions
For each of the variants of development of the sewerage system obtained in this way, financial risks are es-
timated [4]. For this, using the decisionmaking methodology, a "risk matrix" is constructed, which has the form shown in Table 2.
d-400 d-280
' >< I
d=400 d=2E0
« 4 •
d-500 d"400 d-400
• Ы
ФМ
I —
d--|60 d=I2S
. -a d=IM>
A
,d-|60
d=250
d=200 d=J40
•
■
d-500 d=315 ---•
d=450 d=450 d=ÏS0
if* •
λ T= T
4 ÜO j;
«Ht
Isf*—• lo • „
d=355
d-140
d-31S
d=280
^ d-400 о
r#
I *
T3
1м лш> I
i
• • :
^d-250 ^ d -iafl^ -
I ill: second option
Fig. 6. Optimal option of the sewerage system at a design flow load of 421.4 liters per second
d-560 d=400 d=280
d-500 d-400 d=450
I H-
9-
d=125
it •
■öf d=180_ d-14(l
d-180 « •
d=!25
^ d=280 j ¿-225^-180
d=225 d-160
фм
d-500_ d-315_
(M-
d=450_ d=450 d=28j
i
• 3 Ä2 «s »
it i: tris°Ai ti
iOI j
d-160
d-355
Im «» 'J
m ^.d-280 T d-200Ï ■
SI • •
4 -
Im
The third option
Fig. 7. Optimal option of the sewerage system at a design flow load of 556.5 liters per second
Fig. 8. Optimal option of the sewerage system at a design How load of 691.5 liters per second
Технические науки. Строительство / Technical Sciences. Construction
Table 2
Risk matrix
IQ (l/s) 286,4 421,42 556,5 691,5 I million rub.
286,4 0 29,087 54,021 78,277 161,385
421,42 26,417 0 31,144 51,630 109,191
556,5 50,942 24,525 0 35,936 111,403
691,5 73,236 46,819 22,294 0 142,349
Min max 73,236 46,819 54,021 78,277 46,819
In this matrix, the values of the estimated settlement flow loads are presented in the first row and in the first column. On the diagonal are zero values of additional costs, which means the coincidence of the accepted value of flow loads with those that will be after the implementation of the project (option 100% coincidence). The values to the right of the diagonal indicate the risk values from the fact that the actual flow load value after project implementation will be greater than their values assigned in the project. For example, a 286.4 l/s flow rate was chosen for which the sewerage system was designed and built, and at the time of completion, the flow rate was 421.42 l/s, i.e. to 135.02 l/s more. Therefore, an additional reconstruction is required with a present value of 29.09 million rubles per year (see Table 2). If the flow is 691.5 l/s, the risk will already be 78.277 million rubles per year. To the left of the diagonal in the matrix there will be the risk values associated with overestimation of parameters and, therefore, with excessive capital investments. For example, the flow rate was 421.42 l/s, and after the implementation of the project, it was 286.4 l/s. For the
Suppose, for the construction of the first stage, option 2 is selected, which corresponds to a specific consumption of 160 l/person per day. At the
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option with a flow rate of 421.42 liters per second, the cost is 81.512 million rubles per year. For the flow rate of 286.4 l/s the cost is 55.095 million rubles per year. Consequently, the amount of risk is calculated as 81.512 - 55.095 = 26.417 million rubles. The last column of the "risk matrix" presents the maximum risks for each variant of the estimated flow. The last element of this column corresponds to the minimum value of the maximum risks (Savage criterion). Consequently, the option with a total of minimum risks would be the option with a flow rate of 421.42 l/s. If the investments allocated for the first stage of construction are known, for example, 23 million rubles, then the fourth option is excluded from consideration (see Table 3). If these investments amount to 15 million rubles and less, the problem of distributing these investments in the development of the water disposal system is being solved. The result of the calculation will be the costs from consumers, from which it is possible to allocate drains for this money. In our example for 15 million rubles it is possible to divert drains from subscribers in the amount of 213.6 l/s.
Table 3
time of completion, the actual specific consumption may be different, for example 180 l/person per day. Taking into account the actual specific consumption,
Investments for each of the options and for each construction stage
Option Flow load, l/s Investment, (million rub.)
First queue Second queue Third queue
1 286,4 17,850 12,008 12,983
2 421,42 20,002 13,203 14,860
3 556,5 22,584 14,317 16,057
4 691,5 23,939 15,192 17,200
their possible values are again formed for the second and third stages (see figure 2 in green). The membership functions for the second and third construction queues are again made (see figure. 3, d, e). Development options are being formed, a "risk matrix" is being built and a second stage option is being selected. After the completion of the second stage, based on the actual specific water consumption, a forecast is again made for water consumption (see figure 2 in yellow) and the membership function for the third stage of construction is again constructed (figure 3, f), a "risk matrix", etc.
On the basis of the numerical experiments, it can be concluded that for gravity sewerage systems under conditions of uncertainty of prospective wastewater loads, the option with maximum specific water consumption is preferable. This is explained by the fact that the sewers, designed for maximum loads, will drain the minimum flow of waste water, but if the flow is more than estimated, expensive reconstruction will
be required. The pressure sewer can be calculated for minimum and medium loads, since at a flow rate more than the calculated one, it is possible to do without shifts of pressure sewer. It is sufficient in this case to increase pressure and flow rate of the pumping station. If the sewerage system is represented by pressure and gravity sewer, then the answer can be obtained only after carrying out calculations according to the method described above.
Conclusions
A new method for justifying the parameters of developing sewerage systems under conditions of limited investment is proposed, which is formed by investment programs of utilities, under conditions of uncertainty in the specific values of water consumption and diversion of drains and other indicators for which indicative and adaptive management is carried out. This methodology corresponds to market relations, which are penetrating deeper into this vitally important industry - housing and communal services.
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Критерии авторства
Чупин Р.В., Фам Н.М., Горьков Е.А., Мороз М.В. имеют равные авторские права. Чупин Р.В. несет ответственность за плагиат.
Конфликт интересов
Авторы заявляют об отсутствии конфликта интересов.
Contribution
C h upin R.V., Pham Ngoc Minh, Gorkov E.A., Moroz M.V. have conducted the studies, prepared the article for publication. Chupin R.V. bears the responsibility for plagiarism.
Conflict of interests
The authors declare no conflict of interests regarding the publication of this article.
