Vitrified Clay Pipe Engineering Manual • In service in the U.S. for over 200 years • Over 5 Billion linear feet of VCP installed • The longest-lasting, most sustainable pipe material Vitrified Clay Pipe Engineering Manual © 2017 by the National Clay Pipe Institute. Printed in the United States of America. FOREWORD The Vitrified Clay Pipe Engineering Manual has been prepared by the National Clay Pipe Institute (NCPI) and is offered by the member manufacturers of the Institute as an aid to those requiring engineering reference data applicable to the design, construction and testing of sewer systems and other projects in which Vitrified Clay Pipe (VCP) should be used. Design and construction techniques encountered throughout the country are many and varied. Those described here are based on recognized standards and are considered sound. Technical data presented are considered reliable, but no guarantee is made or liability assumed. The recommendations in this Manual should not be substituted for the judgment of a professional engineer experienced in sanitary sewer design as to the best way of achieving specific requirements. The Engineering Staff of NCPI and of its member companies are available to assist the reader. An electronic version of this document, including links to reference materials, is available for download at ncpi.org. National Clay Pipe Institute - 2017 ncpi.org Foreword-1 Foreword Vitrified Clay Pipe Engineering Manual The National Clay Pipe Institute The National Clay Pipe Institute (NCPI), established in 1917 by clay pipe manufacturers, has developed an unmatched expertise in the use of clay pipe for gravity sanitary sewers. As a result of this focus and decades of research and development, the organization is an invaluable resource for engineers. NCPI led the development of factory applied, flexible compression joints and the low pressure air test to verify proper installation and performance of those joints. Today, NCPI is the resource for technical expertise and practical experience in using VCP for open-cut as well as trenchless installations. Research, development, testing and educational outreach continue to be the driving forces for NCPI. The organization has defined best practices for, designing and installing projects with vitrified clay pipe and represents clay pipe manufacturers on the ASTM International (ASTM) C04 Committee on Clay Pipe. History For at least 6,500 years, clay pipe has been used in sanitary sewers. The design standards and planned functions have changed significantly over the last six millennia, but the knowledge base acquired over that period is an important part of the development of clay pipe of the 21st century. Clay pipe has been used in the construction of combined sewers, storm sewers and sanitary sewers in American cities since the early 1800’s. Much of the early pipe was terra cotta and should not be confused with today’s vitrified clay pipe. Vitrification is a critical difference. “Vitrification by definition is the progressive reduction and elimination of porosity of a ceramic composition with the formation of a glass phase as a result of heat treatment,” according to G. Bickley Remmey in his book Firing Ceramics. He goes on to say, “The firing process encompasses chemical and physical changes in the ceramic body accompanied by a loss of porosity and a subsequent increase of density.” The ultimate purpose of firing is to achieve the mechanical bonding of particles (for strength) and consolidation or reduction in porosity (e.g., for impermeability to fluids). In 1915, almost 100-years after clay pipe was introduced in the sewers of major U.S. cities, ASTM accepted the recommendations of the C04 committee as the first tentative specification for sewer design and construction, designated C12, Recommended Practice for Laying Sewer Pipe. For the preceding 100-years there were no accepted standard practices, so the quality of installation was very much determined by individual engineers and their construction teams. It is a testament to those individuals and the clay pipe manufacturers of the day that 200-years later some of those sewers are still in service. Foreword-2 ncpi.org National Clay Pipe Institute - 2017 Vitrified Clay Pipe Engineering Manual Foreword 100 – 200 Years of Service in the U.S. (As of 2015) Years in Service Year Installed Location 200 Years 1815 Washington, DC 175 - 199 Years 1829 Boston, MA Philadelphia, PA 1850 Clinton, IA 1856 Chicago, IL 150 - 174 Years 1861 Cleveland, OH 1866 New York, NY 1868 Erie, PA 1869 Grand Rapids, MI St. Louis, MO 1870 Hartford, CT 1872 Indianapolis, IN 1873 Los Angeles, CA New Haven, CT St. Paul, MN Portland, OR Raleigh, NC 1874 Lawrence, KS 1875 Baltimore, MD Portland, ME 1876 San Francisco, CA Jacksonville, FL Albany, GA St. Joseph, MO 1877 Davenport, IA Kansas City, MO New Bedford, MA Bucyrus, OH 125 – 149 Years 1878 Omaha, NE 1879 Camden, NJ Memphis, TN Parkersburg, WV Providence, RI Nashville, TN 1880 Rome, GA Rockford, IL Terre Haute, IN Sioux City, IA Red Wing, MN Reno, NV Fargo, ND Dallas, TX Denver, CO Napa, CA Sacramento, CA Woodland, CA 1881 Kalamazoo, MI 1884 Le Mars, IA 1888 Salt Lake City, UT 1890 San Jose, CA 1892 Phoenix, AZ Massillon, OH 1895 Highlands, NJ Atlanta, GA Santa Cruz, CA 100 – 124 Years 1904 New Castle, DE 1915 Seattle, WA National Clay Pipe Institute - 2017 ncpi.org Foreword-3 Foreword Vitrified Clay Pipe Engineering Manual The National Clay Pipe Institute and its member companies are proud of their history as early leaders in the acceptance of and participation in ASTM. More than a century of working with the engineering community has led to the development of stringent standards for the manufacture, testing and installation of VCP sanitary sewer pipe. Clay pipe manufacturers today provide a pipe system that is leak-free resulting in the most sustainable and longest-life sanitary sewer product available. For more information about the history of sewers, visit sewerhistory.org. Acknowledgements The National Clay Pipe Institute wishes to acknowledge the following subject matter experts and members of the NCPI Technical Services Committee who have contributed to this edition, both individually and collectively. Veronica Alvarez, EIT David Gill Ed Sikora Lewis Bertalotto Jeremy Haskins, P. E Larry G. Tolby Jeff Boschert, P. E. Amster Howard Bryan Vansell Richard Brandt Steve Matheny, P. E. Tera Arthur Rudy Brandt Todd McClave Michelle Himsel John Butler Joe Parker, PMP Kent Carlson Garrett Richardson We also appreciate the efforts of the many others who generously gave their time and talent throughout the development of this manual. Foreword-4 ncpi.org National Clay Pipe Institute - 2017 Vitrified Clay Pipe Engineering Manual Table of Contents Chapter 1: Vitrified Clay Pipe Properties ● Pipe Specification Considerations ● Manufacturing Process ● Perforated Pipe ● Vitrified Clay Pipe Specification & Testing Standards Chapter 2: Gravity Sewer Design Planning and Layout ● Curvilinear Sewer Design ● Selecting Pipe Sizes ● Manning’s “n” Coefficient Chapter 3: Corrosion, Solvent‐Based Chemicals, Abrasion & High Temperature Applications in Sanitary Sewers Internal and External Corrosion ● Abrasion Resistance ● Solvent Based Chemical Applications ● High Temperature Applications Chapter 4: Structural Analysis of Rigid Conduits, Underground Using the Marston Load Equations for Computing Trench and Tunnel Loads ● Modified Marston Equation When CLSM Bedding is Utilized ● Concentrated and Distributed Superimposed Dead and Live Loading Equations Chapter 5: Trench Load Tables Chapter 6: Structural Design of Rigid Conduits, Underground Rigid Pipe Bearing Strength ● Effect of Trench Width ● Allowable Bedding and Backfill Materials ● Haunch Support ● Bedding Classes and Load Factors ● Design Factor of Safety Chapter 7: Open Trench Construction Excavation ● Trench Shoring ● Foundation Support ● Pipe Installation ● Compaction of Backfill Chapter 8: Jacking Pipe & Trenchless Installation Methods Vitrified Clay Jacking Pipe ● Slurry Microtunneling ● Static Pipe Bursting ● Pilot Tube Method Chapter 9: Construction of Special Structures Manholes ● Pipe Manhole Connections ● Terminal Cleanout Structures Chapter 10: Residential Building Sewers Lateral Sewer Installation ● Tapping an Existing Line Chapter 11: Inspection & estingT Inspection Tools ● Air and Hydrostatic Infiltration Acceptance Testing Chapter 12: Operations & Maintenance Sewer Cleaning ● Hydro-Mechanical Tools Glossary of Terms Index For the most up-to-date information and live links to related materials, see our manual on line at ncpi.org. CHAPTER 1: VITRIFIED CLAY PIPE Figure 1-1: Modern Vitrified Clay Pipe (VCP) with factory-applied, compression joints, which “shall not leak,” per ASTM C425. Properties Vitrified Clay Pipe (VCP) is uniquely suited for gravity sanitary sewers and is the longest lasting sewer pipe available. No other pipe material can match the properties or deliver the long-term value of VCP. Vitrified Clay Pipe attributes: • Rigid Strength • Flexible Watertight Joints • Sustainable • Inert Rigid Strength VCP is categorized as a rigid conduit, which means it has inherent structural strength in the pipe itself. The common method to determine structural strength is a three-edge bearing test, which is measured in pounds of load per linear foot of pipe length. Three-edge bearing capacities Figure 1-2: Three-edge bearing testing for inherent structural strength. increase with larger pipe diameters. Minimum strengths National Clay Pipe Institute