Sanitary Sewer Construction Methodology

The choice among three construction methods for sanitary sewer, open-cut construction (for gravity sewers), pilot tube micro-tunneling (for gravity sewers), and lift station with force main (using horizontal directional drilling method for the installation of the underground sewer pipeline), was evaluated through the lens of sustainable construction. Four major aspects of sustainable construction (social, economic, environmental, and technical) were considered to arrive at the most suitable option for this construction. The social aspect considered public safety and odor as relating to how social life in the community will be affected. The economic aspect considered both the construction cost and the operations and maintenance cost. The environmental evaluation considered greenhouse gas production and noise pollution. The technical aspect considered constructability and the use of specialized equipment. Expert interviews were conducted to evaluate the opinion of diverse stakeholders on the project, including Developers, City Engineers, and the Public. Multi-criteria decision-making (MCDM) criteria (Technique for Order of Preference by Similarity to Ideal Solution, TOPSIS) was used to evaluate the responses received. Analysis of the results showed a difference in preference for the construction method. While Developers and the Public preferred the open-trench construction, City Engineers preferred the pilot tube alternative. Overall, from the present analysis, open-trench construction was the preferred choice for construction. The authors would like to note that the decision to choose a specific method of construction for underground sewer lines is site-specific.