$\%\%$ Discuss the theoretical framework that underpins the planning and execution of large$-$scale civil engineering projects, focusing on the principles and methodologies that ensure successful project delivery. Your response should delve into the project life cycle stages, including feasibility studies, design, procurement, construction, and commissioning. Additionally, address the role of project management techniques such as critical path method $($CPM$)$ and project evaluation and review technique $($PERT$)$ in optimizing timelines and resources. Consider how risk management, quality control, and stakeholder engagement are integrated into the project management process to mitigate potential issues and ensure adherence to budget and schedule constraints. Finally, explore the importance of sustainability and environmental considerations in the context of modern civil engineering projects, highlighting how these factors are incorporated into the planning and operational stages to achieve compliance with regulatory standards and promote long$-$term viability.