$\%\%$Discuss the complexities and challenges involved in the integration of sustainable practices within the operational phase of civil engineering projects. Consider aspects such as environmental impact assessments, lifecycle analysis, and the incorporation of renewable energy sources. How can engineers balance these sustainable practices with the economic and logistical constraints often present in large$-$scale infrastructure projects? Additionally, evaluate the role of governmental regulations and policies in facilitating or hindering the adoption of sustainable operations in civil engineering.