BIM dimensions: example of air blower station at wastewater treatment plant

. The main goal of research is to analyse the prospects for the development of BIM dimensions (3D-7D) in Russia on the example of Water and wastewater industry (WWI) asset. Justification of goal is the insufficient development of industry-specific BIM systems, allowing for different interpretations of its dimensions. The object of research is the air blower station (ABS), the most energy-intensive asset, which typically consumes 62-85% of the energy of WWTP’s. The method is a hypothesis of 3D-7D modeling of water utility asset, presented for the discussions. ABS compressors reduce costs by regulating the air supply due to lifestyle of the population and seasonal environmental conditions (example of simulation results is present). 3D design visualises variant of the reconstruction of the ABS, implemented according to typical project. 4D planning represent the schedule of energy service company, which provides investments and jobs for: design documentation execution, equipment purchase, installation and commissioning of equipment. 5D costs analyses features of the phase in terms of project expertise. 6D sustainability model in practice differs from prediction or forecasting generated by the simulation model of ABS asset, power consumption will be lower up to real (not simulated) technological loads. 7D management analyses possibility of the life cycle cost estimation as strategic advantage of WWI standard. The paper is based on Russian standards. Designing of 3D models are developing on an irregular basis (proactively) in Russia. The mastering of modeling 3D, 4D, 5D based on individual disciplines (as autonomous databases) is self-sufficient today as WWI tusk. The operational nature of WWI enterprises testifies to the development of elements of 6D-7D models.


Introduction
BIM technology for any industry is directed to use not only 3D modeling but also 4D-7D (4D planning, 5D costs, 6D sustainability of operation and maintenance, 7D management) [1,2].Aspects of energy and cost-effective technologies [3,4] are important, considering BIM design projects with high energy consumption at wastewater treatment plants (WWTPs).However, BIM for WWTPs is published quite rarely [5,6] and without focusing on the most energy-intensive object of the water utility -air blower stations (ABS).
Dimensions in information modeling is not limited to the term or meaning "model" [7], so different researchers use other terms: "measurement" [8], "dimensionality" [9], "levels" [10], "stages" [11].Russian design and construction standard SP 331.1325800.2017"Information modeling in construction.Rules for the exchange between information models of objects and models used in software systems" gives definitions of measurements 2D-6D.
For the implementation of BIM in Water and wastewater industry (WWI), it is important to ensure software and its compatibility for solving the problems of the main and auxiliary activities of the water utility [12,13].
In the context of BIM life cycle, it is advisable to choose an object (or asset) of research.Development materials are presented on the example of the most energy-intensive economy of air blower station concentrated on a single site, which consume 62-85% of the energy of WWTPs [14].

Stage -conceptual design
Conceptual design (or Pre-design) stage as method is rather typical for any country.It gives possibility to select acceptable wastewater treatment schemes, individual facilities, compare resource savings and costs.The design of an object cannot be performed in conditions of multivariance.
Released standard GOST R 1.9.393-1.022.21"Sewer treatment facilities.Construction and reconstruction.Basic technical solutions.Requirements for the development, structure and content in order to ensure optimal capital costs and operational performance" was the next document in the package of standards containing requirements for the complete life cycle of WWTP.When creating or reconstructing a WWTP, the problem arises of choosing the optimal technological solutions (OTS) from a number of options with the formation of the approved part of the OTS, specifying the requirements of the design task.This document recommends considering the possibility of developing the OTS as a separate work preceding the development of project documentation.
In the variants of pre-design solutions for air blower stations (ABS), energy efficiency is realized through the use of regulated or controlled compressors (Figure 1): -with rotary-vane mechanisms at the inlet and outlet of compressor; -using a frequency converter (FC); -throttling the flow at the inlet part of compressor.
The main idea of ABS formation is to identify by prognoses the values of energy savings of duty compressors daily and seasonally.ABS compressors reduce costs by regulating the air supply due to lifestyle of the population and seasonal environmental conditions (temperature and humidity).
Figure 1b is formed based on the results of the simulation model, as a pre-design forecast of duty ABS.A mathematical model was formed to justify the energy saving effect [15].The power consumption of the ABS for a period of 1 year (Figure 2) is visualized: bright areas (dense distribution of data) -daytime high technological loads; light areasnight time of low technological loads.Mathematical forecasting of the energy-saving effect of this (Figure 2) real project revealed a reserve of 32,5%, or 11 344 thousand kWh/year.And the research results formed the basis of the energy service contract.

3D design
Figure 3 shows a variant of the reconstruction of the ABS, implemented according to typical project TP 902-9-38.85 of the Soviet time (SoyuzvodokanalNIIproekt). Reconstruction has become a traditional solution in the practice of water utilities, while maintaining the reliability of a capital building and the need to replace the main electromechanical equipment -mainly compressors.The capabilities of this model include the detection of collisions (errors) or problems at the design stage, volumetric visualization of the project, virtual reality technologies (VR), as well as further "as build" laser scan technology after construction.

4D planning, scheduling
The parameter "time" is added to the information model.This allows to plan and manage the construction process, as well as visualize work schedules.The model involves the management of: contractors, procurement, logistics, labor protection and safety.
For the facility, a schedule was developed corresponding to the 4D stage (Figure 4) based on the participation of an energy service company (ESC), which provides investments for: equipment purchase, design documentation execution, installation and commissioning of equipment with stages: -preparation oof Design and estimate documentation and conduct of the tender procedure for the development of; -passing project expertise; -development, approval of Technical task and conclusion of an agreement for an energy service contract; -manufacture and delivery of regulated compressors; -commissioning for compressors; -holding a tender for the supply and construction and installation work of aeration systems in aeration tanks; -installation of automated control systems for air supply (maintaining a given oxygen concentration) to aeration tanks; -technological adjustment of automated control systems for air supply to aeration tanks.Design can include an important element of Industry 4.0 -off-site construction, according to the principle design for manufacturing and assembly (DfMA).The supply of blower equipment is carried out in complete-block products, involving assembly during installation: a set of adjustable compressors with an electric motor, a chamber for replaceable air filters, confusers for connection to air pipes, sensors and instrumentation, noise-absorbing casings, separate control panels and the main control panel.
The use of off-site construction saves time and capital on the construction site, and the fabrication of components in the factory offers a high degree of compatibility construction and installation conditions.

5D costs
The implementation of "cost" parameter allows to evaluate costs in real time and optimize them.This helps to evaluate the budget and estimated cost with time-based costs.
Macro-analysis allows to evaluate costs of labor, equipment, input assets, accounting for estimated costs and expenditure of funds.Micro-analysis will test the budget planning of services against market prices and inflation.Such economic planning helps to visualize the daily expenditure of funds.
FAU Glavgosexpertiza of Russia (expert support and conducting state expertise of project documentation) has begun approving projects and cost estimates in accordance with the methodology for determining the estimated cost of the Ministry of Construction of the Russian Federation (Order of the Ministry of Construction of the Russian Federation No. 421 / pr dated 08/04/2020), the cost of which includes the use of BIM technologies.Currently (2023), Glavgosexpertiza is developing a number of valuable methodologies for determining estimated costs.
Theoretically, a 5D model should be generated automatically when changing the parameters (pipe diameters and lengths, changing equipment and materials, etc.) from 3D model.In practice it's quite difficult to implement, although models are existing and improving.Therefore, the estimates of a specific ABC were formed in the traditional way with usage of quarterly changing indexes of estimated costs, justified by the Ministry of Construction.

6D sustainability of operation and maintenance
The model of operation and maintenance of each water asset includes information about the behavior of the facility in real conditions, monitoring of the state -dispatching, electronic passport of the facility, energy and resource efficiency, repair and maintenance, the need to replace equipment and spare parts or reconstruct individual components of asset.
During implementation of 6D model, the already developed 3D-5D stages are supplemented with a virtual prototype of the "digital twin" of asset or process.The digital twin includes an information database that must be integrated with various IT systems of water utility (SCADA, GIS, etc.).
It is expedient to substantiate 6D models by saving resources in units of consumed electricity (kW•h), reagents (kg•h), heat (kcal•h), etc.These models are intended to save resources under sustainable development.
For proposed object ABC, the result of the 6D model (Figure 5) in practice differs from prediction or forecasting generated by the simulation model, like shown at the Figures 1b,  2. The actual power consumption will be reduced, since the design process loads were used at the early design stages, which is in line with the traditions of design standard SP 32.13330.2018.This position (difference in energy) for the two days shown in the figure 5 was on average 7%, but it can be much more.It should be taken into account that simulation modeling at the 6D stage is performed according to real conditions (temperature, humidity, wastewater flow rates and their concentrations).
In addition, practice reflects the prospects for the development of asset in the extent of reality, as well as calibration of measuring instruments.Thus, the practice of energy and resource conservation is a key issue in 6D dimension.

7D management
Model 7D involves the integration of previous models with asset management in order to achieve stability and reliability of its operation throughout the entire life cycle (includes: information basis for management decisions, implementation of maintenance, risks and guarantees).
The amount of costs and their savings justify the operational and technical indicators of a real asset.A strategic advantage is the availability of the industry standard for water utilities -standard GOST R 58785-2019 "Water quality.Estimation of the life cycle cost for the effective operation of water supply and sanitation systems and facilities".The standard implements the technical and economic basis for making management decisions.The standard contains 10 calculated indicators of the life cycle cost (capital -4 units, operational -5 units) for the period specified by the customer.
Justification of management decisions at the WWI enterprise should be on the basis of currency equivalent (rubles, instead of power in kW•h), using the price of tariffs for electricity at the 7D stage based on real results of the 6D analysis (Figure 5).This level (7D) is usually integrated with a Business Intelligence (BI) tool for sustainable

Discussion
The materials are presented in the form of a hypothesis with the possibility of discussing and correcting the main features of 3D-7D BIM models.Water and wastewater industry (based on water utilities) is clearly experiencing a lack of investment, which hinders BIM development.3D models are developed on an irregular basis, proactively.The industry task of mastering 3D, 4D, 5D modeling based on individual disciplines (as autonomous databases) is self-sufficient today.The operational nature of water utilities evidences the development of elements of 6D models based on data from SCADA and GIS systems, as well as links to the industrial Internet, sensors and data analytics.
No domestic software has been found that allows automating the production of discrete data of nD BIM dimensional models, similar to the foreign CONTEC complex [16].

Conclusion
A hypothesis of 3D-7D modeling of water utility asset is presented on the example of air blower station for the discussions.A specific example demonstrates the mutual relationships and the main features of modeling.The models nD are being developed in water and wastewater industry on an irregular basis, proactively.
Designing of 3D models are developing on an irregular basis (proactively) in Russia.The mastering of modeling 3D, 4D, 5D based on individual disciplines (as autonomous databases) is self-sufficient today as WWI tusk.The operational nature of WWI enterprises testifies to the development of elements of 6D-7D models.

Fig. 1 .Fig. 2 .
Fig. 1.Pre-project conceptual design of energy efficient strategy for air blower station based on regulated compressors: a) formation principle of energy saving; b) design technological regimes of air supply to aeration tanks by unregulated and controlled compressors according to the seasons of the year

Fig. 4 .
Fig. 4. ESC schedule for the reconstruction of ABS asset: from tender procedures to technological adjustment of the facility

Fig. 5 .
Fig. 5. Differences between the 6D-operation model and the stage of design decisions based on forecasting by simulation model of asset ABS