GERMAN ATV RULES AND STANDARDS WASTEWATER - WASTE
STANDARD ATV - A 128E
Standards for the Dimensioning and Design of Stormwater Structures in Combined Sewers April 1992
ABWASSER • ABFALL • GEWÄSSERSCHUTZ GERMAN ASSOCIATION FOR THE WATER ENVIRONMENT
GERMAN ATV RULES AND STANDARDS WASTEWATER - WASTE
STANDARD ATV - A 128E
Standards for the Dimensioning and Design of Stormwater Structures in Combined Sewers April 1992 ISBN 3-934984-17-7
Distribution: GFA Gesellschaft zur Förderung der Abwassertechnik e.V. Theodor-Heuss-Allee 17 • D-53773 Hennef • P. O. Box 11 65 • D-53758 Hennef Tel. 00 49 22 42 / 8 72-120 • Fax: 00 49 22 42 / 8 72-100 E-Mail:
[email protected] • Internet: www.atv.de
ATV-A 128 E The ATV ad hoc Working Group 1.9.1/1.9.3 in the ATV Specialist Committee 1.9 "Assessment and Treatment of Stormwater Discharge", who prepared this ATV Standard A 128, is made up from the following members: Dr.-Ing. Göttle, Kempten, (Chairman) Prof. Dr.-Ing. Brunner, Karlsruhe Dr.-Ing. Durchschlag, Bochum Dipl.-Ing. Freund, Wiesbaden Prof. Dr.-Ing. Geiger, Essen Dr.-Ing. Gniosdorsch, Frankfurt Dipl.-Ing. Jacobi, Darmstadt Dr.-Ing. Meißner, München Dipl.-Ing. Pawlowski, Berlin Dr.-Ing. Pecher, Erkrath Dipl.-Ing. Schitthelm, Düsseldorf Dr.-Ing. Schmitt, Kaiserslautern Dipl.-Ing. Sperling, Essen Dr.-Ing. Verworn, Hannover Dipl.-Ing. Willems, Essen Prof. Dr.-Ing. Wolf, Kassel
The Standard presented here has been prepared within the framework of the ATV committee work, taking into account the ATV Standard A 400 "Principles for the Preparation of Rules and Standards" in the Rules and Standards Wastewater/Wastes, in the January. 1994 .version. With regard to the application of the Rules and Standards, Para. 1 of Point 5 of A 400 includes the following statement "The Rules and Standards are freely available to everyone. An obligation to apply them can result for reasons of legal regulations, contracts or other legal grounds. Whosoever applies them is responsible for the correct application in specific cases. Through the application of the Rules and Standards no one avoids responsibility for his own actions. However, for the user, prima facie evidence shows that he has taken the necessary care.
All rights, in particular those of translation into other languages, are reserved. No part of this Standard may be reproduced in any form by photocopy, microfilm or any other process or transferred or translated into a language usable in machines, in particular data processing machines, without the written approval of the publisher.
Gesellschaft zur Förderung der Abwassertechnik e.V. (GFA), Sankt Augustin 1992
German 0riginal produced by: Druck Carl Weyler KG., Bonn
2
December 1992
ATV-A 128 E
Contents 1
Scope of Application and Terms
7
2
Objective of Stormwater Treatment
7
2.1
Principles
7
2.2
Method of Approach
7
3
Requirements on Stormwater Treatment
8
3.1
Technical Requirements for the Normal Case (Normal Requirements)
8
3.2
Advanced Requirements
9
3.3
Overall Consideration of a Lake or River
9
3.3.1
Common Requirements in the Overall Drainage Area
9
3.3.2
Combined Requirements with Different Surface Waters
10
4
Planning Principles
10
4.1
Reduction of the Amount of Wastewater Produced
10
4.1.1
Rainwater Run-off
10
4.1.2
Domestic and Industrial Wastewater Flow
10
4.1.3
Sewer Infiltration Water Flow
11
4.2
Measures for Wastewater Treatment in the Combined Wastewater System
11
4.2.1
Intermediate Storage of Combined Wastewater
11
4.2.2
Redistribution of Rainfall Run-offs
11
4.2.3
Wastewater Treatment Measures
11
4.3
Structures with Overflow
12
4.3.1
Stormwater Overflows
12
4.3.2
Stormwater Tanks with Overflow
13
4.3.2.1
Stormwater Tanks Retaining the First Flush of Stormwater
14
4.3.2.2
Stormwater Tanks with Overflow for Settled Combined Wastewater
14
4.3.2.3
Composite Tanks
14
4.3.2.4
Sewers with Storage Capacity and Overflow
15
4.3.2.5
Main and By-pass Streams
16
4.3.3
Arrangement of Several Stormwater Tanks with Overflow
19
4.3.3.1
Parallel Stormwater Tanks with Overflow
19
4.3.3.2
Series Stormwater Tanks with Overflow
20
4.3.4
Stormwater Holding Tanks
20
5
Planning Scope
21
5.1
Determination of Actual Status
21
5.2
Determination of the Planning Status
21
5.3
Planning Periods
21
5.4
Standard and Variant Investigations
22
6
Calculation Principles
22
6.1
Sizes of Catchment Areas
22
6.1.1
Annual Precipitation hPr
22
6.1.2
Surface Areas ACA and Ais
22
6.1.3
Flow Time tf
23
6.1.4
Mean Terrain slope group SGm
23
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3
ATV-A 128 E 6.2
Discharges
23
6.2.1
Combined Wastewater Discharge to the Sewage Treatment Plant Qcw
23
6.2.2
Dry weather Flow in Daily Average Qdw24
24
6.2.3
Hourly Peak Flow with Dry Weather Flow Qdwx
24
6.2.4
Rainwater Run-off from Separate Areas QrS24
25
6.2.5
Rainwater Run-off Qr24
25
6.2.6
Critical Rainwater Run-off Qrcrit
25
6.2.7
Critical Combined Water Flow Qcrit
25
6.2.8
Mean Rainwater Run-off During Overflow Qro
26
6.3
Discharge Rates
26
6.3.1
Dry Weather Discharge Rate qdw24
26
6.3.2
Rainwater Run-off Rate qr
26
6.4
Dry Weather Concentration cdwc
27
6.5
Mean Mix ratio in Overflow Water m
27
7
Determination of the Necessary Total Storage Volume
27
7.1
Determination of the Permissible Overflow Rate
27
7.1.1
Influence of Heavy Polluters ap
28
7.1.2
Influence of Annual Precipitation ah
28
7.1.3
Influence of Sewer Deposits aa
29
7.1.4
Dimensioning Concentration in the Dry Weather Flow cd
30
7.1.5
Theoretical Overflow Concentration ccc
30
7.1.6
Permissible Annual Overflow Rate eo
30
7.2
Necessary Total Storage Volumes
32
7.3
Accountable Storage Volumes
33
7.4
Minimum Storage Volumes
33
8
Dimensioning of Individual Structures with Overflow
34
8.1
Simplified Distribution Method
34
8.1.1
Approach
34
8.1.2
Scope of Application
34
8.2
Verification Procedures
35
8.2.1.
Special Basic Facts
35
8.2.1.1
Precipitation Loading
35
8.2.1.2
Registration of the Sewer Network
35
8.2.1.3
Fictitious Central Tanks
36
8.2.2
Approach
36
8.2.2.1
Preliminary Calculation to Determine Permissible, Model-Dependent,Overflow Loads
36
8.2.2.2
Determination of the Rehabilitation Requirement
37
8.2.2.3
Planning of Measures
37
8.2.2.4
Further Verification Parameters
38
8.2.3
Requirements on Pollution Load Calculation Methods
38
9
Dimensioning of Individual Structures with Overflow
39
9.1
Stormwater Overflow
39
9.2
Stormwater Tanks with Overflow
41
4
December 1992
ATV-A 128 E 9.3
Sewer with Storage Capacity and Overflow
42
9.3.1
Sewer with Storage Capacity with Top-end Overflow
42
9.3.2
Sewer with Storage Capacity with Bottom-end Overflow
42
9.4
Stormwater Holding Tanks
42
10
Construction and Operation of Structures With Overflow
43
10.1
Stormwater Overflows
43
10.1.1
General
43
10.1.2
Method of Construction of Stormwater Overflows with Overflow Weirs
44
10.1.3
Method of Construction of Stormwater Overflows with Floor Opening (Spring Overflow)
45
10.2
Stormwater Tanks with Overflow
46
10.2.1
Method of Construction of Separation Structures and Overflows
46
10.2.2
Method of Construction of Stormwater Tanks with Overflow
47
10.2.3
Method of Construction of Sewers with Storage Volume
48
10.2.4
Method of Construction for Discharges
48
10.3
Maintenance and Operation
49
10.3.1
Maintenance Facilities
49
10.3.2
Cleaning and Flushing Facilities
50
10.3.3
Measurement Facilities
50
10.3.4
Other Records
50
11
Dimensioning Example
50
11.1
Local Situation
50
11.2
Necessary Total Storage Volumes
52
11.2.1
Simplified Distribution Procedure
53
11.2.2
Verification Procedure
53
11.2.2.1
Hydrologic Method
56
11.2.2.2
Hydrodynamic Method
56
11.2.2.3
Presentation of Results
57
11.3
Dimensioning of Stormwater Overflows
58
11.3.1
Stormwater Overflow SO1 in Commercial Area 2
58
11.3.2
Stormwater Overflow SO2 in Sub-area 3
58
12
Terms
59
13
References
60
Appendix 1
64
Notes on Advanced Requirements
64
Protection or Management Need
64
Effects
64
Assessment Criteria
66
Measures
67
Further action
67
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ATV-A 128 E Appendix 2
68
Pollution Load Calculation Methods
68
2.
Hydrologic-Empirical Methods
68
3.
Deterministic Models
68
3.1 Hydrologic-Deterministic Models
69
3.2 Hydrologic-Hydrodynamic Models
69
4.
70
Characterisation of Pollution Load Calculation Methods
Appendix 3
72
Appendix 4
73
Calculation Formulas for Figs. 12 and 13
73
Appendix 5
6
Discharge Diagram for the Simplified Dimensioning Procedure (Th. Bettmann) 74
December 1992
ATV-A 128 E
1
Scope of Application and Terms
These Standards apply for structures with overflows in the overall system of a combined wastewater sewer system within the catchment area of sewage treatment plants. It replaces the previous ATV Standard A 128 from 1977/1. Structures with overflows in combined systems are structures with an overflow into a lake or river such as, for example, stormwater overflows (SO), stormwater tanks with overflows (STO) and sewers with storage capacity and overflow (SSCO). Stormwater holding tanks (SHT) are dealt with in ATV Standard A 117. Stormwater sedimentation tanks (SST) serve for the treatment of stormwater with separate systems. They are also not dealt with here. Information is given in the ATV Working Report in "Korrespondenz Abwasser" (1980), Vol. 1.
2
Objective of Stormwater Treatment
For water management and cost reasons the priority task of the planning of measures for wastewater collection and stormwater treatment is the avoidance of stormwater overflow into the sewer system wherever this is possible. For the remaining discharges, for technical water management and economic reasons, stormwater structures with overflow are located in combined wastewater sewers. With precipitation run-off, high pollutant loads can occur which, with discharge into lakes and rivers, could load these heavily. Although the loadings appear only temporarily these can exceed those from the effluents of sewage treatment plants several times over during rainfall run-off. The task of stormwater treatment is so to limit the rainfall run-off into the sewage treatment plants that there the desired effluent values are maintained and, at the same time, the surge-type loadings of the lakes and rivers remain within acceptable limits. The aim of stormwater treatment must be the best possible reduction of the total emissions from stormwater overflows and sewage treatment plants within the scope of water management requirements. An effective protection of lakes and rivers and of sewage treatment plants from excessive loadings is to be expected if the necessary stormwater treatment takes place according to the criteria of these Standards.
2.1
Principles
The objective can be achieved with various formulations - from discharge avoidance to substance retention. Stormwater overflows are fundamentally to be assessed together with the sewage treatment plant for interrelated catchment areas of a section of a lake or river. Requirements on the sewage treatment plant runoffs and on the stormwater overflow installations should be matched in their effectiveness for the lake or river. The regional and network specific quantities precipitation, flow time, gradients, sewage storage capacity, heavy pollutants and areas drained with a separate system have a considerable influence on the overflow quantity and concentration. These are therefore taken into account.
2.2
Method of Approach
Having taken into account the given possibilities of discharge reduction or discharge avoidance, both prerelieved and non-prerelieved overflow structures are to be dimensioned for the remaining discharges. The effectiveness of a stormwater treatment here depends not only on the available storage volume but also particularly on the arrangement, design and operation of the installations (Chaps. 4 and 5). Basically, there two procedures available for the dimensioning and verification of the objective of the stormwater treatment: -
simplified dimensioning procedure using diagrams (Chap. 8.1), verification procedure using pollutant load lculations (Chap. 8.2).
December 1992
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