3.7 Water Pipe

Water mains up to and including 12 inches in nominal diameter shall be constructed of DR 18 AWWA C900 PVC; or externally zinc coated Class 52 ductile iron pipe with V-bio® polyethylene encasement. Alternate materials may be used subject to PUD approval. Material requirements for water mains larger than 12 inches in diameter shall be determined on a case-by-case basis. All water main joints shall be fully restrained per Section 3.13.

New water mains that are provided for future extensions will be sized consistent with the latest version of the PUD’s Water System Plan, as interpreted by PUD staff. For locations not covered by the Water System Plan, PUD staff will determine the necessary size during the development review process. For preliminary planning, size the new main according to the existing grid, or 8 inches in diameter, whichever is larger. Larger mains may be required based on fire flow needs and the water system pressure at a particular location.

In certain cases, the PUD may require a water main that is larger than needed by the development alone. If this oversize main is 12 inches or more in diameter, the PUD may participate in the cost difference between the larger main required, and the size of the main needed for the development alone. To initiate a review of this possible participation, the developer needs to submit a request for participation to the PUD.

Dead end mains 50 feet or shorter to serve only a fire hydrant shall be a minimum of 6 inches in diameter. Dead end runs longer than 50 feet to serve a fire hydrant shall be a minimum 8 inches in diameter.

Dead end mains to the end of a residential cul-de-sac where the water main cannot be extended in the future shall be minimum 8 inches in diameter to the last hydrant and 4 inches in diameter past the last hydrant to the end. The diameter reduction is to minimize the amount of potentially stagnant water in the end of a main and maintain water quality.

All development projects with 3 or more services where the combined public and private service length individually exceeds 100 feet, shall install a 4 inch minimum diameter public water main to serve the project. The water main shall be extended to the nearest property line of the most remotely served parcel of the project.