Rehabilitation and Maintenance of Drains and Sewers / Prof. Dr.-Ing. D. Stein, Dipl.-Ing. R. Stein (2004)

Cross Section Shapes and Dimensions

image
Image 1.4-1:  Standardised sewer cross sections with geometric values for fully filled to DIN 4263 (04.91) [DIN4263:1991]

Sewers with the most varying cross sections and dimensions have been used since the beginning of modern sewage technology and some are still in use to this day.

The most important cross-sectional shapes are the circular, the normal ovoid and the normal arch cross sections (Image 1.4-1).

The circular cross section was and still is preferred in use because of its structural and hydraulic advantages in the nominal size range 100 ≤ DN/ID ≤ 500.

Since the development of reinforced and pre-stressed concrete technology, the progressive improvement of pipe manufacturing and pipe making, pre-finished pipes in circular cross section even up to DN 4000 have been used for main collectors.

DN is the abbreviation for nominal size. It is a characteristic size for circular cross sections measured in mm but without the explicit indication of the mm unit. It approximately corresponds to the internal diameter.

The normal ovoid cross section was used for the first time in 1846 in London and arrived in Germany about 1870 [Frühl10].

Hydraulically, it has particular advantages in the drainage of larger, erratic drain flows, e.g. for combined water sewers with small dry-weather flows.

Together with the arch cross section, it is designated by the axial dimensions of width (b) /height (h) in the millimetre sizes but without indication of the mm unit.

Ovoid cross sections have, and are still being used in the upside down position in order to lower the water level line, to improve the static effects or to make accessibility easier.

In the past years, this sewer cross section has experienced a renaissance because of its static and operational advantages as well as the reduced danger of depositing due to lower velocities. Connected with this are reduced waste emissions in wet weather and better handling of larger waste quantities in the sewage treatment plant in dry weather [White94a] [Braun93] [Sarto89].

Arch cross sections offer advantages for larger flows and restricted construction height. Although the hydraulic efficiency for partial filling is poor, yet the shape is statically advantageous because it approximates the course of the line of pressure.

In particular cases, e.g. in the building of holding sewers, rain holding basins or for defined location collecting points, rectangular cross sections with clear axial dimensions of about 800 mm have been, and are still used. The bottom is sloped laterally (Abschnitt 1.7.7).

Besides these regular cross sections, there is a further range of cross-sectional shapes and sizes (Image 1.4-2) (Image 1.4-3), which were also standardised in the past and are still used in individual cases (Abschnitt 1.7.7).

image
Image 1.4-2:  Non-standardised sewer cross sections with geometric values [ATV82] (Part1)
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Image 1.4-3:  Non-standardised sewer cross sections with geometric values [ATV82] (Part 2)
Table 1.4-1: 
Cross sections and dimensions for sewers to DIN 4263 (07.47/07.77), DIN 4263 (04.91) [DIN4263:1991] and DIN 19540 (12.52/09.64) [DIN19540] - Part 1: Circular cross section
Cross−sectional
designation
System sketch Nominal size DN or b⁄h to
DIN 4263
(07.47)
DIN 19540
(12.52 or
09.64)
DIN 4263
(07.77 or
04.91)
Circular cross
section
100 150 100
125 200 125
150 250 150
200 300 200
250 350 250
300 400 300
350 450 350
400 500 400
450 600 500
500 700 600
600 800 700
700 900 800
800 1000 900
900 1200 1000
1000 1400 1200
1200 1600 1400
1400 1800 1600
1600 2000 1800
1800 2200 2000
2000 2400 2200
2200   2400
2400 2600
2600 2800
2800 3000
3000 3200
  3400
3600
3800
4000
Table 1.4-2: 
Cross sections and dimensions for sewers to DIN 4263 (07.47/07.77), DIN 4263 (04.91) [DIN4263:1991] and DIN 19540 (12.52/09.64) [DIN19540] - Part 2: Ovoid cross sections
Cross−sectional
designation
System sketch Nominal size DN or b⁄h to
DIN 4263
(07.47)
DIN 19540
(12.52 or
09.64)
DIN 4263
(07.77 or
04.91)
Ovoid
cross
sections
1.
Extended
ovoid
cross
section
600⁄1050    
700⁄1225
800⁄1400
900⁄1575
1000⁄1750
2.
Normal
ovoid
cross
section
500⁄750 500⁄750 500⁄750
600⁄900 600⁄900 600⁄900
700⁄1050 700⁄1050 700⁄1050
800⁄1200 800⁄1200 800⁄1200
900⁄1350 900⁄1350 900⁄1350
1000⁄1500 1000⁄1500 1000⁄1500
1200⁄1800 1200⁄1800 1200⁄1800
1400⁄2100 1400⁄2100 1400⁄2100
1600⁄2400   1600⁄2400
3.
Wide
ovoid
cross
section
1000⁄1250  
1200⁄1500
1400⁄1750
1600⁄2000
1800⁄2250
2000⁄2500
2400⁄3000
4.
Squashed
ovoid
cross
section
1200⁄1200
1400⁄1400
1600⁄1600
1800⁄1800
2000⁄2000
2400⁄2400
2800⁄2800
3200⁄3200
Table 1.4-3: 
Cross sections and dimensions for sewers to DIN 4263 (07.47/07.77), DIN 4263 (04.91) [DIN4263:1991] and DIN 19540 (12.52/09.64) [DIN19540] - Part 3: Arch cross sections
Cross−sectional
designation
System sketch Nominal size DN or b⁄h to
DIN 4263
(07.47)
DIN 19540
(12.52 or
09.64)
DIN 4263
(07.77 or
04.91)
Arch
cross
sections
1.
Extended
arch
cross
section
1200⁄1200    
1400⁄1400
1600⁄1600
1800⁄1800
2000⁄2000
2400⁄2400
2800⁄2800
3200⁄3200
2.
Normal
arch
section
1600⁄1200 1600⁄1200 1600⁄1200
1800⁄1350 1800⁄1350 1800⁄1350
2000⁄1500 2000⁄1500 2000⁄1500
2400⁄1800 2400⁄1800 2400⁄1800
2800⁄2100 2800⁄2100 2800⁄2100
3200⁄2400 3200⁄2400 3200⁄2400
3600⁄2700   3600⁄2700
4000⁄3000 4000⁄3000
3.
Squashed
arch
cross
section
2000⁄1250  
2400⁄1500
2800⁄1750
3200⁄2000
400⁄2500
Table 1.4-4: 
Cross sections and dimensions for sewers to DIN 4263 (07.47/07.77), DIN 4263 (04.91) and DIN 19540 (12.52/09.64) - Part 4: Channel cross sections
Cross−sectional
designation
System sketch Nominal size DN or b⁄h to
DIN 4263
(07.47)
DIN 19540
(12.52 or
09.64)
DIN 4263
(07.77 or
04.91)
Channel
cross
sections
1.
One
sided
walkway
1650⁄2200    
1800⁄2400
2100⁄2800
2400⁄3200
2.
Two
sided
walkway
2600⁄2600
2800⁄2800
3200⁄3200
3600⁄3600
image
Image 1.4-4:  Special cross section and associated manhole for the separate system of sewers in Bromberg about 1910 [Braub25] [Büsin12]
image
Image 1.4-5:  Cross sections of masonry sewers of the classes I to IV ("Class sewer") of the Free and Hanseactic City of Hamburg [Hambu79b]

A special cross section for the separate system of the town of Bromberg (today Bydgoszczy) in which the surface water is drained in the upper portion and wastewater in the lower portion, as well as the situation in the region of the special manhole, is shown in (Image 1.4-4).

The masonry sewers of the City of Hamburg are divided into the profile classes I to IV [Hambu79b] whose cross sectional shapes and dimensions can be seen from (Image 1.4-5) or (Table 1.4-1).

Table 1.4-5: 

Dimensions for the cross sections of masonry sewers ("Class sewers") in Hamburg [Hambu79b]

Profiles Clearwidth [m] Clearheight [m] Cleararea [m2]
CL. VI 0.55 1.00 0.43
CL. V 0.70 1.20 0.64
CL. IV 0.85 1.40 0.92
CL. III 1.05 1.55 1.26
CL. II 1.25 1.80 1.76
CL. I 1.55 2.00 2.41

 

Important definitions within any sewers are the minimum sizes whereby guaranteeing the disposal also of coarser and more bulky materials and possibly the accessibility must be considered as relevant criteria.

As regards the first-named criteria, the following minimum dimensions were usual in the year 1910 [Frühl10] :

Berlin Circular cross section 270 mm (earlier 210 mm)

Hanover As Berlin

Leipzig Circular cross section DN 350

Stuttgart Circular cross section DN 300

Frankfurt/Main Circular cross section DN 300 or ovoid cross section 670/1000

Karlsruhe Ovoid cross section 400/600

Munich Circular cross section DN 300 or ovoid cross section 400/600

Today the following minimum nominal sizes are valid in the Federal Republic of Germany [ATV95b] :

  • Drain system DN 150
    (for single houses also DN 125)
  • Laterals to street sewers DN 150
  • Wastewater sewers DN 200
  • Surface water drains DN 250
  • Combined water sewers DN 250

For operating purposes [ATVA118:1977] recommends, independently of the calculated total discharge, that the following minimum nominal sizes of

wastewater sewers DN 250

surface and combined water sewers DN 300

should not be reduced and to limit the minimum diameters to special cases.

An important argument in the determination of the minimum dimensions which carried more weight according to [Frühl10] for instance in France or Vienna up to 1910 than in Germany, was the requirement of accessibility "in order to be able to investigate the inside of the sewer and the house connections which entered into it."

The minimum cross section of 800/1100 in Vienna was too small for this purpose for Frühling [Frühl10]. He therefore recommended that only sewers with a minimum height of 1200 mm and larger should be classed as accessible.

The German "Safety Regulations for Working in Enclosed Spaces of Sewage Installations" [GUV176a] specify:

"Sewers with an ovoid profile of less than 100 cm height and those of circular cross section of less than 90 cm clear width should not be accessed. Exceptions should be made only with special permission and taking special safety precautions into account".

Works in the sense of these safety regulations, for example, are:

  • Inspection works such as testing, regular viewing and measuring;
  • Maintenance works such as cleaning, lubricating, additions, replacements and adjustments;
  • Renewal works such as repairs and replacements;
  • Alteration works;
  • Installation works.

Individual communities in the Federal Republic of Germany only permit these activities in pipelines > DN 1200.

The definition of Accessible Piping in connection with the trenchless construction method (Abschnitt 1.6.2), i.e. manned pipe jacking is contained in [ATVA125a].

Here, as a rule, an inside diameter of at least 1200 mm is required.

In exceptional cases, the inside diameter of the jacking pipe can be reduced to 1000 mm when

  • A drive section of a sewer of 80 m is not exceeded; and
  • A working pipe placed in front of it (inside diameter 1200 mm) of at least 2000 mm

length is available.

In sewer systems, the sewers are laid in stepped cross sectional dimensions. Examples of these types from the cities of Dresden and Berlin are shown in (Image 1.4-6) and (Image 1.4-7).

image
Image 1.4-6:  Sewer cross sections and dimensions of the sewer of the City of Dresden about 1912 [Büsin12]
Top: ovoid cross section.
Bottom: parabolic cross section
image
Image 1.4-7: 
Sewer cross sections of the sewer systems of the City of Berlin about 1890 [Hobre84]

Rehabilitation and Maintenance of Drains and Sewers / Prof. Dr.-Ing. D. Stein, Dipl.-Ing. R. Stein (2004)