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Planning and Design Gravity Sewers

Jerry D. Morrow, P.E.

Course Outline

Gravity sewer design is an area of civil engineering that is often taken for granted. The result can be a 50-year storm or sanitary system that could allow years of inflow and infiltration, deposits and blockages, invert erosion, structural failure and systems that are hydraulically over-loaded, causing flooding and backups.

This course starts with the basics and addresses planning, expected flows, hydraulics, structural pipe design and appurtenances. Tables and Charts and sample problems are provided, so that that student has a practical guide to the successful design of a gravity system.

The course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the reader will:

Intended Audience

This course is intended for civil engineers and technical civil designers.

Benefit to the Audience

Attendees of this course will get a review of the factors that must be considered to plan and design a sanitary sewer system. The class further addresses hydraulic design to establish pipe size, structural analysis to select the proper pipe strength and bedding conditions that support the pipe and discusses appurtenances such as junction boxes and precast manholes.

Course Introduction

Sanitary sewer systems must be properly planned and sound criteria established prior to beginning hard design. The larger the watershed, the more important the planning portion of the exercise. The course establishes design criteria and the engineering necessary to provide a sound design product.

The course work separates sanitary sewer design into:

Sample design problems are presented to allow the attendee to work through a design of the sanitary sewer system for a watershed with nine sub-watersheds. The calculation charts, graphs and design curves are presented to assure the attendee has the tools to undertake the design task as a new designer or provides a good review with a collection of design tools.

The course content can be printed out in MS Word, with embedded charts, drawings and design curves that will provide a future reference document.

Course Content

The course content is in a PDF file Planning and Design Gravity Sewers .

Please click on the above underlined hypertexts to view, download or print the documents for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader.

Course Summary

Often sanitary sewer design is undertaken without evaluation of design periods, downstream receiving systems, and future uses within the watershed. Some basic planning prior to beginning design can greatly improve the longevity of the product.


Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

Take a Quiz

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.