## 2 Literature Review  
### Sewerage Construction Projects Management  
When considering Sewerage construction projects, management problems become subjects of research and study, similar to other types of construction projects. Some noteworthy examples of general problems presented in the literature include the following: an optimization model for sewage rehabilitation aiming to achieve maximum effectiveness at the lowest cost, utilizing genetic algorithms [1]; a methodology for selecting and prioritizing Sewerage projects within available funds and system capacity, based on dynamic programming principles [2]; a study on the risk of cost overruns in water and Sewerage system construction projects [3]; the development of a new method to enhance the accuracy of Monte Carlo simulations and its validation in predicting the success likelihood of Sewerage build-operate-transfer projects, based on eight case studies [4]; research on culturally appropriate organization of projects implemented through public-private partnerships [5]; theoretical and empirical analysis of issues arising in public-private partnership projects within the sewerage sector [6]; and an investigation into delay factors in sewerage projects using simulations and a dynamic systems approach [7]. Cost-related challenges within sewerage projects constitute a distinct area of focus in the research literature. In one study [8], sewerage project cost estimates are examined using two alternative approaches. The first approach integrates component cost ranges and probability values established by a panel of estimators. In contrast, the second approach involves simulating costs based on random numbers, where component values are selected randomly within specified ranges. The study [9] introduces a model that relies on the utilization of prior information for the estimation of operational costs within sewerage systems. Specifically, the authors delve into the process of modeling prior information to furnish preliminary assessments of investment requirements. To facilitate subsequent estimation, the Bayes linear estimator was employed. Another research endeavor [10] centers on the intricacies of cost comparison in wastewater treatment. The authors delve into equitable methods for comparing and allocating costs in municipal sewage treatment concerning their structure and origin. Another study [11] conducts an in-depth analysis of factors responsible for variations and the resulting costs in sewerage construction projects. The work of [12] discloses research outcomes on benchmarking sewerage systems, particularly emphasizing the analysis of investment costs. This also involves an exhaustive examination of intangible variables such as economic fluctuations and tendering strategies and how they influence construction cost calculations. A notable contribution by [13] presents an Excel-based model capable of evaluating costs associated with sewerage system environmental impact. This model comprehensively assesses investigation, investment, design, operation, maintenance, supervision, and overall annual costs. The study seeks to provide a tool to facilitate environmentally informed decisions when selecting wastewater systems. The determination of capital costs for conventional sewerage systems in developing countries is scrutinized in [14]. The analysis involves the examination of unit construction costs expressed as ranges of capital cost values. Ref. [15] presents a literature review on the lifecycle costs of complete sanitation chain systems within developing cities. Moving forward, ref. [16] conducts an analysis of time-cost models that aid in forecasting project durations of different types. The research explores how construction technology influences the relationship between time and cost, particularly focusing on trenchless and open-cut technologies. In the realm of public-private partnership sewerage projects, ref. [17] delves into transaction costs.