Basic Environmental Technology Water Supply Waste Management and

Basic Environmental Technology Water Supply, Waste Management, and Pollution Control SIXTH EDITION CHAPTER 8 Sanitary Sewer Systems Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -1 a) Cross section of a combined sewer; combined sewers, which were built in many older cities, carry both storm and sanitary sewage. A smaller channel at the bottom serves to carry the sanitary sewage at selfcleansing velocities during dry-weather periods. During rainstorms, the storm runoff and sanitary sewage become mixed together. (b) During very heavy rainstorms, most of the combined sanitary and storm sewage must be diverted directly into the receiving stream because it is too much for the treatment plant to handle; this causes water pollution. (c) Separate sewers are used in new construction. (From Waterworld News. Reprinted by permission. Copyright © the American Water Works Association. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -2 Section views of a lateral sewer manhole, which provides access for pipeline inspection, cleaning, repair, and flow sampling or measurement. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -3 Typical outside drop-manhole structure. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -4 When intersecting pipes at a manhole are of different diameters, the pipe crown elevations may be kept the same to allow for a smooth flow transition. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -5 A depressed sewer, or inverted siphon as it is called, is constructed to carry the gravity flow under an obstacle along the pipeline route. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -6 Sanitary sewers are located to provide gravity (downhill) flow as much as possible. It is best to avoid the need for pumping stations. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -7 Typical sewer plan and profile will show the location, depth, diameter, and slope of the pipeline, as well as the location of the other utility lines. (Courtesy of the National Clay Pipe Institute, Elkhorn, WI. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -8 When the sewer pipe diameter and slope are not adequate to carry the peak wastewater flows, the system will temporarily become surcharged. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -9 Sewers cannot always be placed deep enough in the ground to allow gravity flow from all service connections. Individual sewage pumps or ejectors may have to be used by some homeowners. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -10 pipeline. Crown corrosion in unlined concrete sewers can eventually lead to structural collapse of the Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -11 Illustration for Example 8 -2. Basic Environmental Technology, Sixth Edition Jerry

FIGURE 8 -12 Illustration for Example 8 -3. Basic Environmental Technology, Sixth Edition Jerry

FIGURE 8 -13 Lift stations are used to raise the hydraulic grade line in the sewer system. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -14 A wet-well mounted pump station. (Courtesy of Smith and Loveless, Inc. , Lenexa, Kansas. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -15 A dry-well type of lift station. Basic Environmental Technology, Sixth Edition

FIGURE 8 -16 A buried pipeline must be able to resist external forces without excessive deflection or cracking. The load on the pipe due to backfill depends on the type of soil, the depth of cover the pipe crown (H), and the width of the trench (B). Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

TABLE 8 -1 Selected Minimum VCP Crushing Strengths Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -17 Different types of pipe bedding conditions affect the safe supporting strength of the pipe. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -18 Values of the C coefficient used in Marston’s formula. (From Design and Construction of Sanitary and Storm Sewers, with permission of Civil Engineering/American Society of Civil Engineers and the Water Pollution Control Federation. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

TABLE 8 -2 Typical Values of Soil Unit Weights Basic Environmental Technology, Sixth Edition

FIGURE 8 -19 Batter board method of construction for a sewer line. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -20 In modern sewer construction, laser beams are used to establish the specified slope of the pipe; the laser beam is set in the proper horizontal direction with a transit or electronic theodolite. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -21 A series of well points attached to the main header pipe and a pump can be used to dewater a trench that contains groundwater. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -22 An exfiltration test is one method used to judge the watertightness of a new sanitary sewer. Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -23 In small sewers, a sealing packer can be pulled through the line for repair. (From Existing Sewer Evaluation and Rehabilitation, with permission of Civil Engineering/American Society of Civil Engineers and the Water Pollution Control Federation. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -24 In large sewers, workers must enter the line for repairs. (From Existing Sewer Evaluation and Rehabilitation, with permission of Civil Engineering/American Society of Civil Engineers and the Water Pollution Control Federation. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -25 Sliplining is one method used to repair cracked sewers. (From Existing Sewer Evaluation and Rehabilitation, with permission of Civil Engineering/American Society of Civil Engineers and the Water Pollution Control Federation. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -26 Pressure sewer. (Courtesy of U. S. Environmental Protection Agency, 1991) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -27 Typical layout of a vacuum sewer system. (Courtesy of Bilfinger AIRVAC Water Technologies, Inc. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

FIGURE 8 -28 Schematic view of a vacuum sewer piping arrangement. (Courtesy of Bilfinger AIRVAC Water Technologies, Inc. ) Basic Environmental Technology, Sixth Edition Jerry A. Nathanson | Richard A. Schneider Copyright © 2015 by Pearson Education, Inc. All Rights Reserved