Design Guideline for Fiberglass Pipelines Installed Using Horizontal Directional Drilling

Horizontal directional drilling (HDD) is a form of trenchless technology intended to minimize surface damage, restoration requirements, and disruption of vehicular or maritime traffic with little or no interruption of other existing lines or services. Most common pipe materials used in the North American market for HDD construction of water pipelines include steel, polyethylene (PE) materials medium-density polyethylene (MDPE) and high-density polyethylene (HDPE), fusible poly vinyl chloride (FPVC), ductile iron (DI), and fiberglass. Design and installation guidelines are published for different types of installation equipment (e.g., mini-, midi-, and maxi) dependent on the drilling length, pipe size and pipe materials. For example, American Society for Testing and Materials (ASTM) and Plastics Pipe Institute (PPI) publish design and installation guidelines for use of maxi- and mini-HDD for placement of polyethylene pipelines, F1962 standard guide and TR-46 guidelines, respectively. American Society of Civil Engineers (ASCE) publishes a manual of practice (MOP) No. 108, documenting general design and installation practices intended to cover most horizontal directional drilling installations, but primarily cover steel, polyethylene and ductile iron materials. North American Society for Trenchless Technology (NASTT) publishes HDD Good Practices Guidelines, but refers to the PPI and ASCE for pipe stress analysis guidance. As observed, these guidelines do not completely cover the design and stress analyses of HDD pipelines for all possible pipe materials used in the current HDD construction practice. This paper presents a summary of design practices used for different pipe materials, presents a stress analysis and design framework applicable for fiberglass pipes installed using HDD, and briefly explores the possibility of a unified framework applicable for most pipe materials used in current HDD installation practice for water/wastewater industries.