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3507 High Point Drive North <br />Bldg. 1 – Suite E130 <br />Oakdale, MN 55128 <br />Phone: (651) 704-9970 <br />Bolton-Menk.com <br />Document5 <br />MEMORANDUM <br />Date:March 31, 2026 <br />To:Lake Elmo City Council <br />From:Pete Tholen, Public Works Director <br />Nate Stanley, City Engineer <br />Subject:City Watermain Standard – Evaluation of Ductile Iron Versus Polyvinyl Chloride Pipe <br />Lake Elmo, MN <br />At the February 17, 2026 City Council meeting, staff was directed to investigate changing the City <br />Standard for publicly owned watermain pipe from Ductile Iron Pipe (DIP) to Polyvinyl Chloride Pipe (PVC) <br />for open-cut watermain installation. A description of each material is provided; several factors have <br />been considered from an ownership point of view and prioritized based on importance. The following <br />information is based on research and experience related to these materials and how they perform in <br />Minnesota’s climate. <br />Ductile Iron Pipe (DIP) <br />DIP is made from a specific type of cast iron alloy that is engineered to be strong, tough and flexible. The <br />material resists cracking, has high tensile strength, and has capacity to deform (bend) before breaking. <br />The outside of the pipe is coated in an asphaltic material to protect against corrosion and has a cement <br />mortar lining on the inside suitable for potable water to improve hydraulics and prevent corrosion. <br />Conservatively, properly installed DIP should have a lifecycle of 75-100 years with minimal maintenance. <br />Polyvinyl Chloride Pipe (PVC) <br />PVC pipe is made from a synthetic plastic polymer derived from salt and petroleum and can have several <br />additives to create various material properties. The rigid PVC used for watermain (C900/C905) has a high <br />stiffness and strong pressure resistance. The material is corrosion-proof, non-conductive, lightweight, <br />and has a smooth interior for excellent hydraulic performance. Conservatively, properly installed PVC <br />should have a lifecycle of 75-100 years with minimal maintenance. <br />1. Strength and Pressure Capacity <br />DIP has the advantage in this category due to its high structural strength and stiffness, ability to better <br />handle high internal pressure under external loads, and its strength in situations of poor soil support. <br />The lower stiffness of PVC pipe relies more on pipe-soil interaction, and improper installation can result