The latest technical document from the Municipal Advisory Board (MAB) details the required wall thickness for a high-density polyethylene (HDPE) water main pipeline that is subject to the fault crossing seismic hazard. The 38-page MAB-10 2025, Design of HDPE Water Mains for Crossing Seismic Hazard, includes formulas, calculations and charts plus information about pipeline response to strike-slip events. It partners with the previously published MAB-9, Design of HDPE Water Mains for the Lateral Spread Seismic Hazard. Both are available for free on the group’s website: www.plasticpipe.orb/MABpubs
“As requested by multiple owners and consultants, the Municipal Advisory Board developed this document to assist in the design of HDPE for the expected fault crossing seismic event,” stated Camille George Rubeiz, P.E., F. ASCE, co-chair, HDPE Municipal Advisory Board, and vice president for the Plastics Pipe Institute’s (PPI) Municipal & Industrial Division. The MAB serves as an independent, non-commercial adviser to the Municipal & Industrial Division of PPI, the major North American trade association representing the plastic pipe industry.
“In MAB-10 2025, simple relations are developed for the required wall thickness for an HDPE water main subject to the fault crossing seismic hazard,” he continued.
“The two primary seismic hazards to buried pipelines are wave propagation (WP) and permanent ground deformation (PGD). For the fault crossing hazard as described in MAB-10, the required wall thickness is a function of site conditions – burial depth and soil unit weight -, the acceptable pipe strain, and geometric characteristics of the hazard, specifically the amount of fault offset and the pipeline’s fault crossing angle.”
Heat-fused HDPE pipe sections create a leak-free joint and a monolithic pipeline. The ductility and flexibility of HDPE pipe provide high resistance to earthquakes and is also an important factor for ease of installation. The HDPE pipe also resists corrosion and is not subject to tuberculation, important for maintaining and maximizing water flow capacity. HDPE pipe can be installed using a variety of trenchless and open cut methods.
The MAB-10 volunteer task force consisted of multiple engineers, utility professionals, industry experts, and contractors. The project was led by Michael O’Rourke, Professor Emeritus Civil Engineering, Rensselaer Polytechnic Institute. MAB-10 plus other documents can be found at www.plasticpipe.org/MABpub.
