There is an ongoing need to provide designers, specifiers, engineers, consultants and students an overview and general understanding on the proper installation and rehabilitation of buried municipal and industrial pipelines to provide a long-lasting wastewater and potable water infrastructure that will serve future generations.
Goals and Objective
Most buried pipe relies on interaction with the surrounding soil to carry loads. The properly designed pipe and joining system depends on proper soil support, and therefore proper installation, to provide good structural performance. This paper is about pipe types, joint types and soil types and how, through good design and installation, they interact to form effective piping-soil systems. The paper describes the basic structural assumptions that designers make on the installation of rigid and flexible pipe in specific soil conditions. Further, the paper and photographs describe and show the stages in pipeline open trench and trenchless construction – excavating the trench, preparing the foundations, placing the bedding, placing and compacting the embedment soil and back fill to design specifications in the construction of new and the rehabilitation of existing sewers and water transmission systems.
The Institute shared sponsorship of the American Society of Civil Engineers ASCE video and handbook Design and Installation of Buried Pipes and is a voting member of ASTM D 3839 Standard Practice for Underground Installation of Fiberglass Pipe, and AWWA M-45 Fiberglass Pipe Design Manual. The paper is modeled after the installation portion of the ASCE video and addresses the following topics:
a. Types of pipe, their materials and pipe joints. This section distinguishes between pressure and non-pressure pipe, rigid and flexible pipe and an introduction to the types of pipe joints.
b. Site and environmental conditions. This section discusses variations in site topography that may influence the pipe design. Further, it discusses different types of soil types and densities, their strengths and stiffness.
c. Pipe loading and soil interaction. This section discusses how to achieve favorable pressure distributions from soil and other loadings by following good installation practices. Further, there is a discussion on pipe bedding and how it affects rigid and flexible pipe performance.
d. Pipe-soil excavation and construction. This section describes the design of first a foundation layer, next the bedding on which the pipe is placed and the laying of the pipe, then the embedment material placed between the pipe and trench wall and finally the trench backfill.