GERMAN ATV-DVWK RULES AND STANDARDS

STANDARD ATV-DVWK-A 134E

Planning and Construction of Wastewater Pumping Stations June 2000 ISBN 3-937758-45-3

Marketing: GFA Publishing Company of ATV-DVWK Theodor-Heuss-Allee 17 D-53773 Hennef Postfach 11 65 D-53758 Hennef Tel. +49 (0) 22 42 / 872-120 Fax: +49 (0) 22 42 / 872-100 E-Mail: lumma@atv.de Internet: www.gfa-verlag.de

ATV-DVWK-A 134E

2 June 2000

Preparation

This Standard has been elaborated by the ATV-DVWK Specialist Committee ES-3 “Wastewater Pumping Stations” within the ATV-DVWK Main Committee ES “Drainage Systems”.

ATV-DVWK Specialist Committee ES-3 has the following members:

Dr.-Ing. Peter Evers, Essen Dipl.-Ing. Heinz Haendel, München († 1997) Dipl.-Ing. Peter H. Hanitsch, Frankfurt am Main (Vice Chairman) Dipl.-Ing. Günther Koch, Stuttgart Dipl.-Ing. Lutz Naupold, Bremen Dipl.-Ing. Wolfgang Tochtermann, Berlin (Chairman) Dipl.-Ing. Manfred Tornow, Berlin Dipl.-Ing. Bernd Zander, Braunschweig

In addition the following have collaborated:

Dipl.-Ing. Hansjoachim Mahret, Berlin Dipl.-Ing. Dietrich Warnow, Berlin

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 into a language usable in machines, in particular data processing machines – without the written approval of the publisher.

© GFA-Gesellschaft zur Förderung der Abwassertechnik e. V., Hennef 2000

Setting and printing (German original): DCM, Meckenheim

Die Deutsche Bibliothek [The German Library] – CIP-Einheitsaufnahme

Standard. A 134E. Planning and Construction of Wastewater Pumping Stations/[from the ATV Working Group]. – 2000 ISBN 3-937758-45-3

ATV-DVWK-A 134E

June 2000 3

Contents

Preparation...............................................................................................................................................2

User Notes................................................................................................................................................6

Foreword ..................................................................................................................................................6

1 Area of Application ..................................................................................................................6

2 Planning and Dimensioning..................................................................................................7 2.1 Type of Structure and Structural Dimensions of the Pumping Station ......................................7 2.2 Wastewater Inflow......................................................................................................................8 2.3 Ordinates and Pumping Heads..................................................................................................9 2.4 Pumping Task ............................................................................................................................9 2.5 Expansion Possibilities...............................................................................................................9 2.6 Minimum Completely Free Passage ..........................................................................................10 2.7 Flow Rate and Inside Diameter of the Pressure Main ...............................................................10 2.8 Number of Cycles of the Pumping Plant and Dimensioning of the Inlet Chamber ....................11 2.9 Digestion of the Wastewater ......................................................................................................11

3 Structural Engineering ..........................................................................................................11 3.1 Methods of Laying Foundations.................................................................................................11 3.2 Verification of Stability................................................................................................................11 3.3 Building Protective Measures ....................................................................................................12 3.4 Design of the Structure ..............................................................................................................12 3.4.1 Inlet Chamber.............................................................................................................................12 3.4.2 Machinery Room........................................................................................................................12 3.4.3 Superstructure, Entrances .........................................................................................................12 3.4.4 Stairs, Ladders, Step Irons, Platforms .......................................................................................13 3.4.5 Heating/Heat Removal ...............................................................................................................13 3.4.6 Windows, Doors .........................................................................................................................13 3.4.7 Earthing......................................................................................................................................13 3.4.8 Lightning Protection ...................................................................................................................13 3.4.9 External Design and Outside Facilities ......................................................................................14 3.4.10 Connection of Pipelines, Protective Pipes and Similar to the Building ......................................14

4 Mechanical Engineering.........................................................................................................14 4.1 Centrifugal Pumps......................................................................................................................14 4.1.1 Design of the Pumps..................................................................................................................14 4.1.2 Impeller Shapes and Completely Free Passage .......................................................................15 4.1.3 Notes on Design.........................................................................................................................16 4.1.4 Type of Mounting .......................................................................................................................17 4.1.4.1 Horizontally Mounted Pumps (Dry-well Installation) ..................................................................17 4.1.4.2 Vertically Mounted Pumps (Dry-well Installation) ......................................................................18

ATV-DVWK-A 134E

4 June 2000

4.1.4.3 Submerged Pumps (Wet-well Installation) ................................................................................ 18 4.2 Pump Drives.............................................................................................................................. 18 4.2.1 Electric Motors........................................................................................................................... 18 4.2.2 Combustion Engines ................................................................................................................. 20 4.3 Pipelines in the Pumping Station .............................................................................................. 20 4.4 Gate Valves............................................................................................................................... 21 4.4.1 Gate Valves with Elastomer Coated Obturators ....................................................................... 23 4.4.2 Parallel Slide Gate Valves......................................................................................................... 23 4.4.3 Tapered Gate valves ................................................................................................................. 23 4.5 Non-return Valves ..................................................................................................................... 24 4.6 Pump Air Bleeding..................................................................................................................... 24 4.7 Admission Gate Valves ............................................................................................................. 24 4.8 Water Supply Facilities.............................................................................................................. 25 4.9 Washdown Facilities.................................................................................................................. 25 4.10 Machinery room Drainage......................................................................................................... 25 4.11 Ventilation Facilities for Machinery Rooms ............................................................................... 26 4.12 Ventilation Facilities for Inlet Chambers................................................................................... 26 4.13 Lifting Gear................................................................................................................................ 27

5 Electrical Engineering............................................................................................................ 27 5.1 External and Structural Prerequisites........................................................................................ 27 5.2 Energy Supply ........................................................................................................................... 28 5.2.1 Energy Supply with a Voltage up to 1000 V (Low Voltage) ...................................................... 28 5.2.2 Energy Supply with a Voltage over 1000 V (Medium High Voltage)......................................... 29 5.2.3 Measurement of Consumption .................................................................................................. 30 5.3 Switchboard Plant, Actuators and Appliances .......................................................................... 30 5.3.1 Main Drives................................................................................................................................ 30 5.3.2 Ancillary Drives.......................................................................................................................... 31 5.3.3 Ancillary Facilities...................................................................................................................... 31 5.3.4 Operating and Measuring System............................................................................................. 31 5.4 Emergency Power Supply ......................................................................................................... 31 5.5 Types of Protection and Regulations ........................................................................................ 32 5.5.1 Explosion Protection.................................................................................................................. 32 5.5.2 Protection against Accidental Contact ..................................................................................... 32

6 Measurement Engineering ..................................................................................................... 33 6.1 Level Measuring Systems ......................................................................................................... 33 6.2 Delivery Pressure Measuring Systems ..................................................................................... 33 6.3 Flow Measuring Systems .......................................................................................................... 33 6.4 Transmission of Measured Values............................................................................................ 33

7 Wastewater Pressure Pipelines ............................................................................................. 33 7.1 Pressure Pipelines .................................................................................................................... 33 7.2 Pipeline Routes ......................................................................................................................... 34 7.3 Dimensioning............................................................................................................................. 34 7.4 Stresses..................................................................................................................................... 35 7.5 Pipe Materials............................................................................................................................ 35 7.6 Corrosion and Corrosion Protection.......................................................................................... 35

ATV-DVWK-A 134E

June 2000 5

8 Commissioning ........................................................................................................................36 8.1 Pumping Station.........................................................................................................................36 8.2 Pressure Main ............................................................................................................................36

9 Information on Standard Specifications, Directives, Standards, Advisory Leaflets (Selection).................................................................................................................................37

9.1 General Terms and Conditions for Engineering Services, (VOB)..............................................37 9.2 Standard Specifications .............................................................................................................37 9.2.1 Building Standards .....................................................................................................................38 9.2.2 Pipes and Fittings.......................................................................................................................38 9.2.3 Mechanical Engineering.............................................................................................................39 9.2.4 Measurement Technology..........................................................................................................39 9.2.5 Electrical Engineering ................................................................................................................40 9.3 Directives, Standards and Advisory Leaflets .............................................................................41 9.3.1 of the ATV ..................................................................................................................................41 9.3.2 of the DVGW ..............................................................................................................................41 9.3.3 des VDI.......................................................................................................................................41 9.3.4 of the VDMA [German Association of Mechanical Engineering Establishments] ......................42

10 Annexes ....................................................................................................................................42 Annex 1: Example of a pumping station with centrifugal pumps in horizontal, dry-well installation ........43 Annex 2: Basic circuit diagram..................................................................................................................48

ATV-DVWK-A 134E

6 June 2000

User Notes

This Standard is the result of honorary, technical-scientific/economic collaboration which has been achieved in accordance with the principles appli-cable therefor (statutes, rules of procedure of the ATV-DVWK and the Standard ATV-DVWK-A 400E). For this, according to precedents, there ex-ists an actual presumption that it is textually and technically correct and also generally recognised.

The application of this Standard is open to every-one. However, an obligation for application can arise from legal or administrative regulations, a contract or other legal reason.

This Standard is an important, however, not the sole source of information for correct solutions. With its application no one avoids responsibility for his own action or for the correct application in spe-cific cases; this applies in particular for the correct handling of the margins described in the Standard.

Foreword

Standard Specification EN 752-6 “Drainage sys-tems outside buildings”, Part 6 “Pumping stations”, elaborated by its Technical Committee TC 165 “Wastewater Engineering”, has been issued by the European Committee for Standardisation (CEN). It was to be adopted into the German Standards as DIN EN 752-6. Supplementary to this the earlier Standard ATV-A 134 “Planning and Construction of Wastewater Pumping Stations with Small In-flows” has been revised and expanded by ATV Specialist Committee 1.3 “Wastewater pumping stations”, so that it can be applied, like the stan-dard specification, for small and large wastewater pumping stations including their pressure mains.

Standard ATV-DVWK-A 134E supplements Standard Specification EN 752-6 and provides advanced information and proposals as to how, taking account of economic aspects, pumping stations can be planned and built. EN 1671 is to be applied for pumping stations with pressure drainage.

It deals exclusively with the employment of cen-trifugal pumps for the conveyance of wastewater, for which they are mainly employed. This does not,

however, exclude other delivery plant (see “Kom-munale Abwasserpumpwerke” [Municipal waste-water pumping stations], Vulkan-Verlag,). State-ments made here also apply equally for such pumping stations so far as they do not demand other technical solutions. It would be beyond the framework of the Standard to go into these in de-tail.

Conveyor spirals with their completely different de-livery principle and thus also other structural con-cept are also dispensed with, although it is just these which are relatively frequently employed to raise wastewater before the wastewater treatment plant.

The special requirements affecting these are laid down in Standard Specification DIN 1184 Part 4 “Pumping stations; Archimedean screw pumps; di-rectives for planning”. Taking into account the wastewater-specific requirements (e.g. explosion protection) indicated in this Standard, these apply equally for wastewater pumping stations.

Facilities in the field of wastewater as a rule are used for a long time. They must, in addition, have a high availability for the protection of surface wa-ters against pollution and for the securing of local hygiene. Great significance is given to ideas on quality. Cost reductions are possible. They may, however, not be at the expense of the environ-ment.

With a comparison both investment costs as well as operating costs are always to be considered with the annual costs arising from both compo-nents.

1 Area of Application

The pumping station, with the discharge of waste-water, has its particular significance in that, through the avoidance of too deep a position, it can improve the economic efficiency of a drainage system. It is extensively independent of topog-raphical conditions and makes it possible to feed effluents into receiving waters and sewers even at high levels. Furthermore, using pumping stations, wastewater can be conveyed for widely spread catchment areas to treatment facilities sited at suitable locations.

ATV-DVWK-A 134E

June 2000 7

Wastewater pumps, which are mainly installed in the tank facilities (see ATV-A 166 [Not available in English]), are also frequently employed for the sur-face feeding and, in particular, for the emptying of stormwater tanks. The Standard applies analo-gously for these, however the technical require-ments are to be matched to the tank-specific re-quirements (e. g. impeller shape, completely free passage, no continuous operation).

Pumping stations are also suitable for control of flow in larger networks.

It is emphasised, that this Standard is not to be employed where special drainage methods are used. These cases are dealt with in Standard ATV-A 116E.

2 Planning and Dimensioning

The pumping station has to be so dimensioned that, with the taking into account of sufficient reserves the same disposal security as with discharge under gravity is achieved.

The basic requirements to be placed on a wastewater pump are an automatic, fault-free operation with which the unhygienic and haz-ardous maintenance tasks remain limited to a minimum.

The initial considerations to be made for planning and dimensioning, the relevant factors for the se-lection of terrain or location as well as the decisive criteria for the dimensioning and equipping of the pumping station are presented in detail in EN 752. The following notes serve as supplement.

The layouts of the routes for the supply and disposal pipelines and the method of their lay-ing are to be agreed with the authorities repre-senting public interests. Rights of way for pe-destrians, vehicles and pipelines are, if necessary, to be agreed.

2.1 Type of Structure and Structural Dimensions of the Pumping Station

The type of structure and the structural dimensions are determined by the pumping tasks (see Section 2.4), the type of pump installation (wet- or dry-well) and corresponding with the equipping through the associated scope of ancillary facilities (transformer room, switchboard plant, tank farm), other ancillary facilities (fixed crane, heating and ventilation plants, standby plant) as well as, if required, further necessary ancillary rooms (stores, workshops) and social rooms. The arrangement of the pumps in dry-well installation (vertical or horizontal) has ef-fects on the dimensions of the building.

As a rule, wastewater pumping stations are equipped with centrifugal pumps. They are not self-priming and therefore should be installed sufficiently low so that the water flows in under gravity in order to avoid being subject to ab-normal occurrences. Fundamentally at least two pumps should be installed.

Before the decision as to whether the pumps should be installed with wet- or dry-wells, the plan-ner should clarify with later operation the differ-ences in construction, equipping and, in particular, operation of the pumping station.

With wet-well installation safety against flooding and lower investment costs are up against in-creased unhygienic and in part hazardous mainte-nance work with greater expense with personnel.

In addition, the decision has to be made whether the pumping station should be provided with a su-perstructure (see Section 3.4.3).

In flood areas the superstructure must be so designed that, with flooding, an endangering of the pumping station is excluded.

For smaller pumping stations there are also pre-fabricated stations as a complete design. They must meet the requirements placed here.

ATV-DVWK-A 134E

8 June 2000

Examples for the different types of construction are presented in Figs. 1 and 2 and in Appendix 1.

Fig. 1: Examples for types of pumping station construction with pumps in dry-well installation

Fig. 2: Examples of types of pumping station construction with pumps in wet-well installation

Before the decision is made on a solution, in addition to the technical, environmentally rele-vant, operational, personnel, social, energetic and other criteria, the financial and economic effects of the possible variants must also be taken into consideration. In addition to invest-ment costs it is essential that the operating and capital costs are included in the consideration of economic efficiency.

2.2 Wastewater Inflow

The daily inflow of wastewater has to be ascer-tained for the determination of the size of the pumping station. It is influenced by:

- the type of drainage method (combined or separate),

- size and structure of the catchment area, - number of inhabitants,

ATV-DVWK-A 134E

June 2000 9

- number and type of connected industrial and commercial concerns.

The inflow is presented in a hydrograph, which re-flects the inflow of wastewater in the course of a day (see Figs. 3 and 4).

Fig. 3: Examples of inflow hydrographs with dry weather, mainly residential area

Fig. 4: Examples of inflow hydrographs with dry weather, strong industrial influ-ence

There can be considerable differences both in the characteristics and in the daily quantities between working and non-working days. With rainfall one has to reckon with an increased yield of wastewa-ter (see ATV-A 118E).

The hydrograph is the basis for the arrangement of the delivery plant (determination of the operating points, selection of the type of pumps, decision on the employment of drives with one, several or vari-able rotational speeds).

2.3 Ordinates and Pumping Heads

The ordinate of the invert of the inflow sewer, the switch-on and switch-off ordinate of the pumps, the outlet ordinate of the pumping destination and the gradient of the terrain between pumping station and the pumping destination are of considerable significance in order to be able to dimension a pumping station.

The pumping head, in addition to the pure static heights, also includes the friction losses which are determined depending on the speed of the medium being pumped as well as the inside diameter and length of the pressure main. In addition, with the delivery by several pumping stations into a com-mon pressure main, depending on the current op-eration of the individual stations different pumping heads arise which influence the arrangement of the pumps (see Section 4.1.1).

2.4 Pumping Task

As pumping task can be, for example, the function as pump-over station (delivery of the wastewater into another catchment area), connecting pump station (delivery into a pressure main network to-gether with other pumping stations), pumping sta-tion ahead of a wastewater treatment plant, empty-ing of stormwater tanks etc.

The effects of the delivery flows on the down-stream drainage system (gravity or pressure main system) with possible further connected systems and the wastewater treatment systems, are to be taken into account with the employment of waste-water pumping stations. Here, not only hydraulic aspects such as, for example, discharge capacity (overloading due to unfavourable layout of the pipeline, height and/or dimension) play a role but also the actual status of the drains concerned, i.e. renovations are possibly to be undertaken.

2.5 Expansion Possibilities

With planning it is to be considered whether, in the course of time, the required delivery flow has to be increased. If this is the case, then the possibility of a later expansion must be taken into account. It can, for example, be sufficient, taking into account

ATV-DVWK-A 134E

10 June 2000

the motor output, later to increase the revolutions of the centrifugal pump which is driven via belt drives or to enlarge the impeller of the centrifugal pump; under certain circumstances, however, room for a larger or additional machine must also be planned within the structure. Equally the laying of an additional pipeline can also be necessary (see also Section 7.3).

2.6 Minimum Completely Free Passage

Experience has shown that, with sewer networks, a formation of textile balls cannot be excluded. Nevertheless, one can dispense with screens in so far as suitable types of pump and sufficient free cross-section are selected in the complete delivery facility.

In order to guarantee a secure delivery a com-pletely free passage of 100 mm both for the deliv-ery installation as well as for fittings and the pres-sure main are recommended. The use of specially developed, blockage-free impellers with a free cross-section of less than 100 mm (see Section 4) and appropriate selection of the pipeline diameter is to be examined.

The pumps of smaller wastewater pumping sta-tions therefore are not only to be dimensioned ac-cording to inflows but insensitivity to blockage and minimum speed are also relevant parameters. This can, in relation to the wastewater inflow, lead to over-dimensioning of the pumps.

An inside diameter of 80 mm for the pressure main should not be undercut.

Smaller completely free passages combined with shredders and appropriate pipeline diameters should only be used in special cases, for example for the disposal of waste from individual real estate, when the connection to a central plant is sought for water management, technical or economic reasons (see ATV-A 116E, ATV-A 200 [Not available in Eng-lish]). Shredded materials can lead to increased de-posits in sewers and pressure mains. Various prob-lems can also occur in the wastewater treatment plant with increased production of shredded mate-rial. The employment of shredders should therefore be clarified, already with the planning, with the op-

erator and, if necessary, with the approval authori-ties.

2.7 Flow Rate and Inside Diameter of the Pressure Main

The following aspects are to be taken into account with the determination of the flow rate in the main:

The lower limit of the flow rate should lie between 0.5 m/s with larger and 1.0 m/s with smaller total delivery times of the connected pumping stations. Depending on the composition of the wastewater higher flow rates must be selected with longer downtimes.

A too low a flow rate leads to deposits and thus to reductions of the cross-section so that the danger of blockage increases.

The highest speed of the delivery flow is depend-ent on the nominal width. For a pipeline length of up to ca. 500 m the following speeds should not be undercut:

Inside diameter in mm 80 100 150 200 Speed in m/s 2.0 2.0 2.2 2.4 Delivery in l/s 10 16 40 75

Flow rates greater than 2.5 m/s should be avoided.

With pipelines of more than 500 m length appro-priately lower speeds are to be preferred to avoid unacceptable pressure surges, for example with pump failure. Investigation of pressure surge should be undertaken.

The optimum nominal width is to be determined through an efficiency calculation and this com-pared with the above guidance values.

With the determination of the diameter of the pres-sure main attention is to be paid that the inside dia-meter of a pipe can deviate considerably from the nominal width depending on the material.

ATV-DVWK-A 134E

June 2000 11

2.8 Number of Cycles of the Pumping Plant and Dimensioning of the Inlet Chamber

The available volume of the inlet chamber for the employment of centrifugal pumps with fixed revolu-tions results as follows between switch-on and switch-off levels:

ZQ

0.9V pm=

V = volume in m3 Qpm = mean pump delivery flow in l/s Z = number of cycles per hour

A number of cycles of 15 per hour should not be exceeded.

The number of cycles is dependent on the stability of the mechanical and electrical plant components, in particular the electric motors (see Section 5.3).

2.9 Digestion of the Wastewater

With comparatively small daily delivery quantities and long pressure mains the retention time of the wastewater in the pressure main is very large and therefore the danger of digestion of the wastewater is present. There is strong odour development and the aggressiveness of the wastewater increases. The possible biogenic hydrogen sulphide corrosion has to be taken into account with the selection of pipe material.

Detailed information for countermeasures is given in Advisory Leaflet ATV-M 168 [Not available in English].

3 Structural Engineering

Pumping stations, elevators and pumping points are structures which consist of an underground part and, as far as possible, an over ground part. Prefabricated shafts are also used for the construction of smaller wastewater pumping stations.

The type of subsoil and the groundwater conditions are decisive contributory factors for determining the type of construction work.

3.1 Methods of Laying Foundations

Before start of construction, investigations of the subsoil and existing underground buildings are to be carried out. Firmly planned construc-tion projects of other parties in the vicinity must also be taken into consideration.

As essential assessment criteria the following are to be determined:

- type of soil (cohesive, non-cohesive, non-plastic and similar in accordance with DIN 18196 and DIN 18300),

- soil structure (inclusions of all types), - bearing capacity, - settlement behaviour, - groundwater (rush, variations in level, utilisa-

tion or non-utilisation), - surrounding buildings, - load carrying traffic areas, - aggressiveness of soil and groundwater, - contaminated sites. According to the thus determined conditions vari-ous methods for the construction of the under-ground part are possible:

- sloped excavation, - revetted excavation (e. g. Berlin lining), - excavation with pile sheeting, - well-foundation (caisson), - compressed air foundation work.

3.2 Verification of Stability

Stability is to be verified for

- the excavation and - the structure itself.

With this it can be necessary to carry out verifica-tion for the construction state (e.g. safety against buoyancy) and for the finished state separately.

The concrete must be impermeable to water in accordance with DIN 1045 and show high resis-tance against chemical attack through the em-

ATV-DVWK-A 134E

12 June 2000

ployment of cements with high resistance to sulphate in accordance with DIN 1164, Part 1. Assumptions about loads are to be made in ac-cordance with DIN 1055. To limit the width of cracks and for improved crack distribution a method of conservation of crack limitation is to be planned. The concrete covering in the under-ground part should be at least 4 cm.

For safety against buoyancy, calculations must be carried out with the factor µ = 1.1, whereby the highest possible level of the groundwater or the high water level is to be taken into ac-count. Here the soil friction or the weight of the demountable assemblies my not be taken into ac-count. Verification of water pressure is to be car-ried out for both internal and external water pres-sure.

The highest possible water level in the inlet chamber must be assumed to be the upper sur-face of the ground.

As one has to reckon with wastewater with ag-gressive substances the values in DIN 4030 are to be observed for the evaluation of the level of attack.

As a rule the upper limiting values are to be taken into account in order to make allowance for a pos-sible unfavourable change of the composition of the wastewater (for some considerable time one has ascertained damage to existing buildings which can be traced back to a change in composi-tion of the wastewater). Therefore, in accordance with the provisions of DIN 1045 on concrete cov-ers, the water-cement ratio, concrete texture and similar are to be taken into account.

3.3 Building Protective Measures

The best protective effect is achieved through the quality of the material itself. With very aggressive water or soil characteristics or the danger of bio-genic hydrogen sulphide corrosion additional pro-tective measures in the form of coats of paint, coatings or sheathing can be necessary.

3.4 Design of the Structure

(For this see Annex 1)

Fundamentally attention is to be paid to suffi-cient entrances secure against flooding and free space around the operational installations which have to be served, maintained and/or re-paired.

3.4.1 Inlet Chamber

Inlets in the inlet chamber are to be so designed that the following are avoided:

- entry of air into the pumps, - stripping of gases, - accumulations of solids on installations and - unfavourable streaming of the pumps.

The inlet chamber is to be so designed that no dead space results and depositing is avoided (slope ≥ 60°). With the employment of concrete this is to be compacted carefully and covered with a compound screed using cement with a high re-sistance to sulphide and is to be smoothed. In special cases an additional acid resistant coating or a ceramic sheeting can be sensible. Enclosed inlet chambers must be equipped with an effec-tive ventilation (see Section 4.12). With regard to inlet chamber space see Section 2.8.

3.4.2 Machinery Room

The dimensions of the room result from the dimen-sions of the machines, the free space around the machines and the space requirement for stairs. For the pumps, assembly holes are to be arranged in the roof above them. The floor is to be made as far as possible anti-skid. A pump well (see Section 4.10) for draining the pump room is to be planned. See Section 4.11 with regard to ventilation.

3.4.3 Superstructure, Entrances

The superstructure with entrances must be se-cure against flooding. It enables the accom-modation of:

ATV-DVWK-A 134E

June 2000 13

- electrical plant, - standby equipment, - stationary ventilation plant, - spare parts, - non-stationary operational equipment, - social facilities

and guarantees at all times a weather-independent and secure access to the pumps and inlet cham-ber.

Requirement for space for the energy supply plant (see Section 5.2) is to be taken into account.

The inlet chamber and the associated ventilator room must be accessible from outside and their doors must be capable of being opened outwards only. Access from the pump room is not permitted.

Only the switch room and the toilets are to be ac-cessible via the pump room. A crane rail or shackle, dimensioned for the largest assembly part, is to be provided in the ceiling. With larger pumping stations a crane system can also be nec-essary (see Section 4.13).

All rooms are to be so equipped that they require little maintenance and servicing.

3.4.4 Stairs, Ladders, Step Irons, Platforms

Pump rooms which are not at ground level should be provided with stairs. Steep and spiral stairways should be avoided, i.e. they are an alternative only with tight space conditions.

The stairs are to be designed according to the re-commendations of the agency responsible for ac-cident insurance. Climbing ladders and climbing irons are to be installed in exceptional cases only. Above 5 m total length they are basically to be provided with a system to prevent falling. Above the entrance points with ladders are to be provided with insertible or extendable stay bars of at least 1 m in length or handholds.

Vertical ladders in the inlet chamber should not be permanently mounted below the water level, but should be foldable or removable. They may not be made of aluminium. In the place of a back protec-

tion, vertical ladders are to be equipped with a pro-tective rail or other safety device. With particularly deep inlet chambers it is recommended that an in-termediate platform be installed. As for handrails, corrosion resistant steel Material No. 1.4571 is equally suitable.

3.4.5 Heating/Heat Removal

All rooms are to be maintained frost-free. The heat emitted by the electrical plant and equipment is to be included with the calculation of the heat requirement. In special cases a heat removal can be necessary (see also Section 5.3.1).

3.4.6 Windows, Doors

Windows and doors are to be designed as far as possible secure against break-in and damage. Windows can be dispensed with if sufficient aera-tion and ventilation as well as lighting of the rooms can be provided alternatively.

3.4.7 Earthing

The earthing device is to be so dimensioned that, in the case of a fault, the currents to earth do not exceed the earth potential of 50 V with alternating current and 120 V with direct cur-rent. In order to achieve the necessary resis-tance, foundation earth connectors are to be laid in buildings and, if required, additionally lattice networks are to be laid in open ground. VDE [Association of German Electrical Engi-neers] regulations are to be observed (see Sec-tion 5.5).

3.4.8 Lightning Protection

For the protection of people and plant pumping station buildings must be provided with a lightning protection system. Here, in accordance with the ABB [German Committee for Lightning Conductor Construction], the metallic construction components of roofs and facades can be included in the lightning protection system both for collector devices and for conducting, if these are reliably connected to this. The conductors of the lightning

ATV-DVWK-A 134E

14 June 2000

protection system are to be connected with the earthing system via “spacers” (see Section 5.5).

For further prevention of damage through the ef-fects of a lightning strike the lightning protection system should be installed in accordance with the Standard Specification DIN IEC 61024-1-2, VDE 0185 Part 102 (see Annex 2).

3.4.9 External Design and Outside Fa-cilities

The route to the pumping station is to be matched suitably in width and surfacing to the local re-quirements.

The superstructure is to be matched in size and form and in the materials employed, for example for the outer façade, with the surroundings. Planted strips several metres wide have proved their usefulness as visual and emission protection (see Annex 1). With a view to later maintenance of the outside facilities, attention is to be paid in the planning that these cause the lowest possible ex-pense.

With sensitive locations it is recommended that ar-chitects and landscape gardeners are already in-volved with the planning.

3.4.10 Connection of Pipelines, Protective Pipes and Similar to the Building

Every rigid pipeline laid underground, which is fixed between two points with different subsi-dence characteristics must be connected flexi-bly. This applies, for example, for inflow sewers which run from the inlet structure to the pumping station.

Pipe fairleads through walls and roofs are to be suitably sealed.

4 Mechanical Engineering

4.1 Centrifugal Pumps

4.1.1 Design of the Pumps

Section 2 “Planning and Dimensioning” is relevant for the design of the pumps. The delivery head is made up of:

- the difference in height (Hgeo) between the highest point in the pressure side of the system and the water level in the inlet chamber,

- the admission pressure (Hadm), e. g. through conveyance in an already otherwise streamed pressure pipeline, and

- the pressure loss (Hloss) in the pipes and fit-tings.

Due to changes in level in the outlet and in the inlet chamber as well as a varying admission pressure there results a range of the pipeline characteristic curves in accordance with Fig. 5.

The operating range of the pump lies between the intersection point of the throttle curve with the highest and lowest pipe characteristic curve. In the case of a compound or parallel operation, attention is to be paid for an as steep as possible throttle curve with the selection of the pump.

Fig. 5: Pumping diagram centrifugal pump

ATV-DVWK-A 134E

June 2000 15

The matching of a changed inflow can be under-taken through the modification of the revolutions and, in addition, through change of the impeller di-ameter.

With all pumps the cavitation behaviour should be examined in order to avoid cavitation, noises, er-ratic running and material wear.

A measure for the cavitation behaviour is the NPSH value (net positive suction head), i.e. the net energy head (= absolute energy head less the va-porisation pressure head) in the entry cross-section of the pump impeller. The NPSH value of the plant (NPSHP) is compared with the NPSH value of the pump (NPSHR). In every case the drop must be NPSHP > NPSHR.

The NPSHR value must be given by the pump manufacturer. The ratio

1.3NPSHRNPSHP

≥

should be sought for security against cavitation with water pumps.

Further details can be taken from DIN 24260, Part 1 “Centrifugal pumps and centrifugal pump sys-tems” [Not available in English].

4.1.2 Impeller Shapes and Completely Free Passage

For the conveyance of untreated wastewater with coarse and fibrous constituents specially shaped impellers are employed (see Figs. 6 to 9) which, to a great extent, prevent blockages and the forma-tion of clogs.

The non-clog impeller is employed as single and multi-port non-clog impeller.

The single port non-clog impeller (see Fig. 6) has the following characteristics:

- constant completely free passage from the en-trance to the intake to the exit to the pressure pipe corresponding to the completely free pas-sage of the impeller,

- efficiency as a rule less than with multi-port non-clog impellers,

- hydraulic out-of-balance, which can only be extensively compensated, and this at great ex-pense, related to a defined operation point. A rate of rotation above 1450 min-1 should be avoided, with large impellers a rate of rotation of 1000 min-1 should not be exceeded.

Fig. 6: Single port non-clog impeller

The multi-port non-clog impeller (see Fig. 7) is, as a rule, a two or three port non-clog impeller. In comparison with the single port non-clog impeller it is characterised by the following features:

- greater delivery heads are achieved. - a static and dynamic balancing is relatively

simple to carry out. Higher rates of rotation, and due to this, greater delivery heads are also possible.

- variable speed operation is without problem. - noise- and vibration-free running is easier to

achieve.

It is, however, more susceptible to blockage than the single port non-clog impeller as, with the same delivery flow, the completely free passage of the impeller channels are smaller.

ATV-DVWK-A 134E

16 June 2000

Fig. 7: Multi-port non-clog impeller

The spiral non-clog impeller (see Fig. 8) is a semi-axial single-vane impeller with helicoidal or screw formed inlet component. It runs very quietly and therefore is employed with rotational speeds of 3000 min-1.

Fig. 8: Spiral non-clog impeller

The non-chokable impeller (see Fig. 9) effects the transport medium indirectly only. With the convey-ance of wastewater it can be employed with rota-tional speeds up to 3000 min-1. The characteristic curve is usually flatter and the efficiency lower than with the other impellers.

Fig. 9: Non-chokable impeller

All given impeller shapes are, in principle, suitable for employment in screenless pumping stations, under the assumption that the requirements of Section 2.6 are met. They are employed normally up to the following pressure values in the point of operation:

- single-port non-clog impeller up to 4 bar, - spiral non-clog impeller up to 6 bar, - multi-port non-clog impeller up to 10 bar, - non-chokable impeller up to 10 bar.

The rate of flow in the impeller channels should, as far as possible, not undercut 2 m/s as otherwise the danger of pump blockage is very great.

4.1.3 Notes on Design

With a dry-well wastewater pump (see Fig. 10) suf-ficiently large cleaning ports are provided on the in-take and outlet to the pressure pipe so that block-ages can be removed from inside the pumps manually. With smaller pumps the size of the cleaning ports should approach the nominal width of the pumps. With larger pumps they should be 180 to 200 mm.

ATV-DVWK-A 134E

June 2000 17

Fig. 10: Cross-section of a horizontally mounted centrifugal pump

Longer downtimes and possibilities of repair are achieved through an exchangeable obturator in the area of the suction mouth of the pump casing and a locking ring on the reverse side of the impeller. In principle, with large pumps, they should be pro-vided. With these an exchangeable obturator is recommended also on the pressure side, i.e. on the bearing side of the pump casing.

Attention is to be paid that every impeller is pro-vided with vanes on the back or pressure side of the impeller disk.

The sealing of the pump in the area of the shaft can be achieved using gland or axial face seals. If a gland seal is used then attention is to be paid that the shaft protective covering is highly wear re-sistant and packings are easy to exchange without greater dismantling.

Assessment criteria with the employment of axial face seals, also with pumps with submersible mo-tor, are a short separation between impeller and first bearing and the employment of specially formed axial face seals which, in particular, do not allow wastewater to penetrate to the contact pres-sure rings of the seals (danger of contamination). A transmitter which signals a possible entry of wa-ter into the sealing oil which lubricates and cools the axial face seal as well as preventing immediate entry of water into the machinery room, should be installed.

4.1.4 Type of Mounting

With the installation of the pumps a differentiation must be made between horizontal and vertical pumps. Submersible motor-driven pumps can also be employed in dry-well installation and thus, with suitable arrangement of the electrical connections, ensure the pumping of wastewater even with flood-ing of the pump room. With its employment in dry-well installation the question of heatremoval from the motor is to be clarified with the pump manufac-turer.

4.1.4.1 Horizontally Mounted Pumps (Dry-well Installation)

In the horizontal layout (see Fig. 11) there is the space saving design of the pump with saddle mounted motorist which, moreover, offers even more advantages.

In this way, with the drive of the pump via v-belts, an easy matching to a possibly changed inflow is possible by changing the transmission ratio; moni-toring and certain repairs on the pump are signifi-cantly more simple.

The pump should have a base frame. The bracket for the mounting of the electric motor is to secured with bolts so that it is removable.

ATV-DVWK-A 134E

18 June 2000

Fig. 11: Dry-well and horizontally mounted centrifugal pump with fitted motor

To tension the v-belts the motor must be mounted so that it is adjustable. Through the compact con-struction the unit is substantial insensitive to vibra-tion. The installation of a pump with motor in modular construction is also possible.

4.1.4.2 Vertically Mounted Pumps (Dry-well Installation)

Fig. 12: Dry-well and vertically installed cen-trifugal pump

The vertical type of installation (see Fig. 12) offers a greater security against flooding through the high mounting of the electrical motor.

The connection between pump and motor is always to be elastic for the acceptance of ad-justment tolerances and for the damping of vi-bration and impact.

4.1.4.3 Submerged Pumps (Wet-well Installation)

If a submersible motor-driven pump in wet-well in-stallation (see Fig. 13) is employed, then attention is to be given to certain peculiarities. Inlet cham-bers are explosion endangered zones. In accor-dance with the regulations of the [German] Asso-ciation for Social Insurance against Occupational Accidents (VBG) pump casings and components, in contact with water, made from aluminium alloys in explosion endangered plant components of wastewater treatment plants of Zones 0 and 1 are not permitted. Fundamentally the motor must be protected against explosion in accordance with VDE 0170/0171, and that is, as a rule, in E Ex dll BT3. cleaning ports on the casing are ruled out. Every wet-well installed pump should be capable of being installed and removed without emptying the inlet chamber and without tightening or loosen-ing of bolts on their pressure joints. The mounting parts required for this are subjected to corrosive at-tack to a particularly high degree. They should be made from stainless steel Material No. 1.4571; this also applies to nuts, bolts and washers.

4.2 Pump Drives

Electric motors are almost exclusively employed for driving the pumps. However, for reasons of dis-posal security, an uncertain energy supply or to cover peaks it can be necessary to employ another type of drive, for example, combustion engines.

4.2.1 Electric Motors

For centrifugal pumps the electric motors should be designed (see Section 5.3.1) for the limiting power requirement of the specified operating range. The same applies for the coupling between pump and motor. Where an increasing wastewater

ATV-DVWK-A 134E

June 2000 19

production is to be expected it is, however, sensi-ble possibly to design the motor and the coupling more robustly, in any case, however, the associ-ated electrical parts of the plant, in accordance with the expansion capacity of the pump.

The following reserve capacities should be pro-vided as a minimum with regard to a sufficient en-gine power to avoid blocking of the impeller:

With pressure mains with elevator effect and such which, with every start-up, have to be completely or in part primed, the increased necessary power

requirement for this is additionally to be taken into account.

Power requirement of the pump in kW

Reserve capacity of the driving motor

up to 7.5 ca. 50%

7.5 – 20 ca. 25%

20 -50 ca. 15%

over 50 ca. 10%

Fig. 13: Section of a wet-well and vertically installed submerged motor pump

It is to be examined whether special measures are necessary for the protection of the pressure mains against possible pressure surges (see Section 2.7) or in order to avoid inadmissibly high currents at make of the pump motors.

To these belongs the so-called smooth starter for cage rotor motors. It prevents undesired load peaks for pumps and motors.

It should be equipped with the reverse function, i.e. a smooth coast down.

If, in addition to a smooth start and coast down, the revolutions are also variable then the em-ployment of a static frequency converter is rec-ommend. Using this, submersible motors and ex-plosion protected motors can be operated with variable revolutions. The possible change of revolutions is to be clarified with the pump manu-facturer. Here the flow rate in the impeller channels is to be noted (see Section 4.1.2).

With the employment of a static frequency con-verter, due to the increased heat loss, the motor should have a reserve capacity of 10 to 15 %. With low revolutions an external ventilation of the

ATV-DVWK-A 134E

20 June 2000

motor can be necessary. In order to protect it from inadmissible heating the windings should be monitored using thermofeelers, i.e. so-called positors.

4.2.2 Combustion Engines

As a rule, diesel motors with a nominal speed of 1500 min-1 are employed as combustion engines. Their speed is adjustable but, for economic run-ning the adjustable speed range used should not go below 75 % of the nominal speed, this means that, under certain circumstances, a mechanical intermediate gear becomes necessary.

For low capacities motor and gearbox often form one unit which is connected with the pump by means of an elastic coupling.

With diesel engines of higher performance, gear-box and pump are to be connected using an elas-tic coupling. The connection between diesel en-gine and gearbox should be via a universal joint shaft. It can counterbalance axle variations which, after longer periods of time, cannot be ex-cluded with respectively separate foundations.

A reverse rotation of the diesel engine is to be prevented under all circumstances!

Mainly water-cooled diesel engines with internal and external cooling water circuits are employed. Oil coolers for gearboxes of higher performance are to be included in the cooling system.

To remove the radiated heat of the diesel engines and to introduce sufficient combustion air the rooms in which they are installed are to be pro-vided with air inlet and outlet openings for outside air. With diesel engines of higher performance and/or smaller rooms inlet and outlet air blowers can additionally be necessary.

Precautionary measures for winter operation are to be taken

Diesel plants create high noise levels; this means that structural measures are to be taken in the interest of the operating staff and the environment. The approval authorities will, under certain circumstances, issue requirements. The scope of the measures to be taken depends

on the position of the installation room and the usage identification of the area in the land devel-opment plan in which the pumping station lies The measures to be taken include:

- structure-borne damping machine mountings, - structure-borne and airborne noise damping

designs in the exhaust discharge system, - airborne noise inhibiting structures in the inlet

and outlet air lines, - airborne noise damping outfitting of walls,

ceilings and doors. The exhaust lines are to be insulated using an appropriate material which guarantees a surface temperature of the finished insulation of ≤ 70°C.

It is to be clarified with the approval authorities which limiting values of atmospheric pollution in the diesel exhaust gas must be met. It is possible that soot filters or catalytic exhaust gas cleaners could be required.

The diesel engine plant must satisfy the pro-visions of the valid ordinances of the [Ger-man] Technical Instructions Air (TA Luft) and Noise (TA Lärm) of the Federal German Im-mission Protection Law.

Fuel storage is also to be planned for energy sup-ply of the diesel motor. It should consist of storage tanks and a service tank. The service tank should be arranged at a sufficient height so that the fuel flows to the diesel engine.

For a secure operation of diesel engine plants a certain number of operational monitoring mes-sages are unavoidable. To these belong:

- fuel tank overfilled, - lack of fuel, - cooling water temperature too high, - lack of cooling water, - lubricating oil pressure too low or lack of lu-

bricating oil (emergency shutdown!).

4.3 Pipelines in the Pumping Station

For the proper operation of dry-well installed pumps the suction (inlet) pipeline must al-ways be laid inclined upwards to the pump. The nominal width of the suction pipeline should

ATV-DVWK-A 134E

June 2000 21

be at least the diameter of the intake mouth of the pump and be not less than 100 mm. A check valve and, following this, a gate valve are to be provided, looking in the direction of flow, on the pressure side of the pump.

Similarly, with a dry-well installed pump, a gate valve should always be inserted in the suction line. Only in this way is it ensured that, with the removal of a blockage or repair of a pump or of a check valve, that pumping operation does not have to be interrupted.

The integration of the pump pressure mains must always be horizontally into the main pipeline (see Fig. 14), as otherwise the vertical pipeline becomes clogged.

Fig. 14: Integration of the pump pressure main

A pressure pipe emergency connection should be provided for a transportable pump for the case of pump room flooding or of total pump failure. The emergency connection should be provided flood-ing- and frost-free in at least DN 100 and as short, vertically upwards, easily accessible con-nection piece with gate valve and blind flange.

Using steel as the pipe material for pressure mains within the pumping station, for reasons of corrosion, this should be thick-walled. Then an in-ternal wall corrosion protection can be dispensed with. With wet-well installation of pumps and where later renovations are possible under diffi-cult conditions only, the employment of Material No. 1.4571 is recommended.

Pipeline fixtures should be arranged with short separation and be made particularly stable. With longer pipelines they should be displaceable axi-ally (heat expansion). The pipelines must, in addi-tion, always be so anchored that they transfer no forces to the pump.

For perfect assembly, i.e. for stress-free connec-tion, for the balancing of length tolerances and to avoid damage to seals, depending on the re-quirements, loose or fixed detachable fittings or compensators should be incorporated in the pipe-lines. Detachable fittings can, however, also be avoided through suitable arrangement of the pipeline, so that pipe elbows with flanges can take over their task.

All painting is to be carried out with the observa-tion of Advisory Leaflet ATV-M 263 (Not available in English).

Larger wall fairleads are, if absolute sealing is re-quired (e.g. against groundwater), to be carried out as wall flanged pipes with one or more wall flanges. In principle these are to be built-in from the start as, with later installation sealing problems can occur.

4.4 Gate Valves

With gate valves it is differentiated between mod-els with internal and external spindle threads (see Fig. 15).

ATV-DVWK-A 134E

22 June 2000

Internal spindle threads External spindle threads

Fig. 15: Tapered gate valves with respectively internal ad external spindle threads

Preferred is the model with external spindle threads as, through removal of the spindle nut and the spindle thread from the area of the wastewater, heavy wear is avoided and the spindle is easy to grease. Nevertheless the greater installation height is to be noted. Ductile cast iron (DCI) is to be pre-ferred to grey cast iron (GCI) as casing material due to the essentially greater security against frac-ture.

Attention is to be paid, with gate valves with me-chanical drive, that the maximum possible actuat-ing power cannot damage the gate valve.

To avoid corrosion on components of the gate valve the following materials are recommended for use in wastewater:

Spindle: Stainless steel Mat. No. 1.4571

Spindle nut: Zinc-free cast bronze

Mat. No. 2.1060

Seating ring: Zinc-free cast bronze

Mat. No. 2.1060

Due to their design tapered and parallel slide gate valves are especially suited for a controlled closure and opening (see EN 752-6, Section 9.3)

Clack valves are not suited for wastewater as tex-tiles can wrap around spindle and swing valve and can prevent the closure procedure.

ATV-DVWK-A 134E

June 2000 23

4.4.1 Gate Valves with Elastomer Coated Obturators

These gate valves have a straight valve opening without valve pocket and an elastic seal (see Fig. 16).

They are particularly suitable as gate valve every-where where they are almost exclusively open.

Deposits which have settled and hardened in the valve pocket with tapered gate valves (applies only with horizontal mounting) are thus avoided. Gate valves with elastomer coated obturators, however, are not suitable as throttles.

Fig. 16: Gate valves with elastomer coated obturators

The dimensions of the gate valve with elastomer coated obturator, depending on the nominal pres-sure, correspond with the tapered gate valves. Ma-terials for spindle and spindle nut here also should be the above given.

4.4.2 Parallel Slide Gate Valves

Parallel slide gate valves (see Fig. 17) are charac-terised by the following advantages:

- very short construction length, - all installation positions are permitted, - easy adjustment of the parallel slide seal,

- spindle and spindle nut are located outside the wastewater stream even with non-rising spindles,

- the parallel slide gate valve can also be supplied as throttle valve,

- cutting effect with solid matter in the wastewater,

- cost efficient.

Fig. 17: Parallel slide gate valve

4.4.3 Tapered Gate valves

The tapered gate valve (see Fig. 15) is very robust and has proved itself in rough wastewater opera-tion. The exception here is, however, the gate valve with two-part (elastic) wedge with which the slider can become clogged with textiles.

Gate valves are standardised up to DN 600 in DIN 3352, Parts 1 – 8.

ATV-DVWK-A 134E

24 June 2000

4.5 Non-return Valves

The non-return valve, when fully opened, may not hinder the passage of solid matter. For this the check valve with a casing made of grey cast iron or ductile cast iron is particularly suitable (see Fig. 18). The later is to be preferred. It should be fitted with lever and weight. With this it offers the possi-

bility of assessing the output of the pump. With small nominal widths (< 150 mm) with low static head of water a backwashing can also be intro-duced by raising the flap by means of the lever. Where a check valve fails due to too small a de-gree of opening as a result of small flow rates, a ball check valve should be employed.

Fig. 18: Check valve

4.6 Pump Air Bleeding

Through conveyance of the centrifugal pump up to the inlet side breakdown of the pumping flow or through leaking glands a dry-well installed cen-trifugal pump empties itself into the inlet chamber after shutting down. Should the return valve be lo-cated immediately or just slightly above the pump pressure connection piece the pump casing re-mains filled with air.

As centrifugal pumps in such a state cannot nor-mally pump they must be bled of air beforehand. For this the bleed line with horizontally mounted pumps must run from the highest point of the pump casing or, with vertically mounted pumps, as short as possible in front of the return valve.

The bleed line should end in the inlet chamber. With this it is to be led so high in the pump room that even with maximum water level in the inlet chamber a perfect bleeding of the air is possible (see Annex 1).

To avoid pumping into the bypass through the bleed line and its blocking, that will certainly occur within the shortest time, the line within the machinery room must have a shut-off de-vice, which automatically closes with the start-up of the pump and, with the shutdown of the pump, opens with a time delay (time until the impeller of the pump has stopped turning). So-lenoid or pinch valves are suitable as shut-off devices.

Where a return valve is located so high that the air from the pump can be forced into the pressure main through the rising water level no bleed line is necessary. With wet-well installed submersible mo-tor-driven pumps this is often the case.

4.7 Admission Gate Valves

For the following reasons it is necessary to sepa-rate the inlet chamber of a pumping station from the inflow:

ATV-DVWK-A 134E

June 2000 25

- for cleaning tasks in the inlet chamber or for the removal of bulky items and solid matter from the inlet chamber,

- for visual checks in the inlet chamber as well as examination of the level switch and other measuring equipment in the inlet chamber as well as measuring runs for the determination of the pump conveyance flow,

- to dry out the inlet chamber for necessary maintenance tasks.

Therefore, from the very beginning, an admis-sion gate valve should be planned with the construction of a wastewater pumping station. With a small wastewater pumping station manual operation as far as possible using an above ground column should be sufficient. With a larger works the gate valve should have an electric actuator, explosion protected in the Class E Ex dII BT3. The most suitable gate valve is one without casing with external threaded spindle, which can be installed in a sewer manhole. Due to water-tightness it is to be so installed in the manhole shaft that the slider plate is pressed against the frame by the water, i.e. from the inflow side.

Threaded spindle, rods as well as all bolts and all anchor bolts, should be manufactured from Mate-rial No. 1.4571 or equivalent. The seals and guides should be made from a zinc-free bronze, for ex-ample Material No. Nr. 2.1060.

4.8 Water Supply Facilities

In accordance with VBG 54 [Regulations of the Trade Association] (UVV 25) [Accident Preven-tion Ordinance] washing facilities with running water must be available in pumping stations. Further details are to be found in the Implementa-tion Instructions to the VBG 54 (ZH 1/177). In addi-tion, water for cleaning purposes in the machinery room and inlet chamber is, in particular required (see also Section 4.9).

With the installation of water supply facilities potable and non-potable water connections must be differentiated.

If a potable water connection is intended then, in addition to the respective regulations of the Federal German States and water supply con-

cerns, DIN 1988 as well as the DVGW [German Technical and Scientific Association for Gas and Water] Standard W 345 must also be ob-served.

4.9 Washdown Facilities

A supply of water should be provided in order to be able to clean the pump room of a pumping station with dry-well installed pumps.

To clean the inlet chamber an output of from 4 to 6 m3/h is required. A fire hydrant is ideal as water source to which a DN 25 hose with D-spout in ac-cordance with DIN 14365 can be connected.

Due to the danger of corrosion the washdown pipeline in the inlet chamber should be made from PE Hard plastic in accordance with DIN 19533 or stainless steel Material No. 1.4571, PN 10.

Attachment of the pipeline should take place also using plastic, or better, stainless steel (Material No. 1.4571 or equivalent) clips. The bolts/screws used for this must also be made implicitly from stainless steel of the same quality.

The washdown pipeline in the inlet chamber may be connected with a potable water pipeline in accordance with DIN 1988, Part 4, only indi-rectly via a water tank and a downstream booster system. Only a pipe disconnector ap-proved by the DVGW which automatically and visi-bly establishes a 20 mm long break in the pipe as soon as the water pressure falls below a certain safety value may also be employed in short-term operation. DIN 1988, Part 5, gives further informa-tion.

With several plants of the same type a transport-able washdown facility, if required equipped with water tank, can also be employed.

4.10 Machinery room Drainage

For the discharge of leaking water and/or washdown water and for the draining of pumps a pump well is to be provided at the deepest point of the machinery room and a light sub-mersible motor-driven pump with the greatest pos-

ATV-DVWK-A 134E

26 June 2000

sible free impeller passage and automatic level switch is to be so connected to a fixed pipe that, with blockage, it can be removed easily and cleaned at any time by hand. The pipeline must be so laid that a siphoning over to the machin-ery room is prevented, i.e. as a rule using a gooseneck via the highest possible ordinate of the backwater of the wastewater inflow.

The drainage pump should have a return valve immediately behind the pressure hose. The instal-lation of a gate valve in the fixed pipeline is useful.

The size of the pump well depends on the pump selected. It should not undercut the dimensions 500 x 500 mm and a depth of 300 mm.

4.11 Ventilation Facilities for Machinery Rooms

In accordance with VBG 54 (UVV 25) rooms of wastewater treatment systems as well as stormwater tanks and pump pits (inlet cham-bers) must be equipped with an effective venti-lation. Details on the type of ventilation are to be found in the Implementation Instruction of the VBG 54.

With an above-ground structure usually the win-dows and, additionally, shaft ventilation suffices for small machinery rooms. All air inlet and outlet openings to the outside are to be provided with protective screens for birds and weather, whereby the protective screen for weather must be seated outside of the protective screen for birds. Further information is contained in VDI [Association of German Engineers] Standard 3803.

If a machinery room lies well below ground level then a five times the hourly forced air exchange should be sought. This is most usefully achieved using an exhaust fan and appropriate air resupply openings.

4.12 Ventilation Facilities for Inlet Chambers

Enclosed rooms of wastewater discharge facili-ties and pump wells (inlet chambers) must be

equipped in accordance with VBG 54 with ef-fective ventilation (see Section 4.11).

For the inlet chamber of small wastewater pumping stations a stationary or transportable mechanical aerator is, as a rule, sufficient. The displaced air must be able to flow via a sufficiently dimensioned free cross-section. With larger pumping stations both a mechanical aerator as well as an air extrac-tor should be installed.

Fundamentally with ventilation plants attention is to be paid that no short circuits form between inflow and outflow air areas.

Both the external inflow as well as the outflow openings are to be so arranged that the neighbourhood is neither hazarded nor incon-venienced by exiting gases. With pumping sta-tions with superstructure they should be as high as possible, whereby the outlet of the outgoing air channel should be located above the ridge of the roof (as far as available), that is outside a possible lee of the wind.

For practical purposes the ventilators should be permanently installed in separate above-ground rooms. These rooms are, as is also the inlet chamber, to be considered as explosion endan-gered and therefore must receive a natural diago-nal ventilation.

All horizontal air channels are to be laid with a slight gradient so that any condensed water that forms can run off to the ventilator or inlet chamber respectively. Every ventilator itself is to be pro-vided with an outlet pipe at the lowest point of its casing, which exits into the ventilation channel to the inlet chamber. Thus it is avoided that water which, under certain circumstances, can even freeze, can collect in the ventilator and lead to its destruction.

All channel sections and naturally also the connection to the ventilator must be joined, sealed, with each other. Firms involved in as-sembly are to be informed urgently on this point.

Air distribution must be so designed that the air can exit both ca. 1 m above the floor of the empty inlet chamber and also above the maxi-mum water level of the inlet chamber.

ATV-DVWK-A 134E

June 2000 27

Ventilators and air channels are to be manufac-tured from corrosion resistant material.

4.13 Lifting Gear

Crane systems are required for the installation and removal of machinery. With smaller pumping sta-tions without superstructure it is to be examined whether mobile lifting gear can be employed, oth-erwise a slewing pillar crane should be provided. In smaller pumping stations with superstructure the lifting device can be designed as single-beam crane trolley with suspended pulley block. With this, the crane girder is to be so directed that the heaviest plant component can be placed directly on to the assembly point. With larger pumping sta-tions a double-beam travelling crane with crane trolley should be installed in the machinery room. With this a picking up and setting down of a load is possible in the complete area of the room. While longitudinal and transverse movement is entirely possible by hand an electrical drive for lifting is a particular advantage when pumps are installed very deep. To be noted is, that for crane sys-tems > 1 t which are permanently installed, a crane maintenance platform, which can be in-stalled transportable or fixed, is essential for maintenance, repair and the legally prescribed tests.

The height and weight of the machine parts includ-ing securing and overall height of the lifting gear, the crane trolley and the crane carrier are to be checked for the dimensioning of the crane system and clear height of the superstructure. Here thought is to be given to possible expansion of the machine plant.

Statics must take into account all working and con-stant loads.

Before first commissioning, following building modifications and with lifting gear for loads greater than 1 t, the complete crane system must be tested once a year by a specialist.

5 Electrical Engineering

(for this see also Annex 2)

5.1 External and Structural Prerequi-sites

Electro-technical installations, in particular switchboard plant, must be housed dry, free of dust and pollutants.

If electro-technical devices are installed as switch boxes in the open, attention must be additionally paid to their maintenance-friendly accessibility as well as to protection against damage through road traffic or vandalism. Switchboard plant and trans-formers may not be installed in areas endangered by flooding.

Rooms with electro-technical installations are to be aerated and ventilated as well as heated so that their function remains assured.

Electro-technical plant may be accessible for a very limited circle of trained or specially instructed technical personnel only. The electrical opera-tional rooms and also the switching plant, so far as it is not installed in electrical operational rooms, must be kept under lock and key.

All doors to electrical operational rooms must be equipped with a panic lock (escape lock), which can be opened from inside, even when locked, without aids.

Information for the design and dimensioning of electrical operational rooms can be found in the VDE Regulations.

Allowance should be made for the protection of structures from oil, acids, overpressure as well as for fire protection.

Floor coverings must be insulated and secure against electrical breakdown for the corre-sponding operational voltages. The coverings may not lead to a build-up of static electricity.

ATV-DVWK-A 134E

28 June 2000

5.2 Energy Supply

The energy supply as a rule is from the low voltage network (400/230 V, 50 Hz) of the responsible ESC (= energy supply company). It can, however, be also required from the medium high voltage network 20, 10 or 6 kV, in exceptional cases 30 kV and more. If a particularly high operational or sup-ply security respectively is necessary, one should provide two independent feeders, laid on two sepa-rate cable routes and secured against simultane-ous connection (considerable additional costs!).

For the securing of the electrical energy supply of a wastewater pumping station the connected load must be determined and contact made with the re-sponsible ESC as early as possible.

The clarification of the supply conditions must take place with the responsible ESC immedi-ately after establishment of the essential con-sumers, that is at a very stage, as they have a

considerable influence on the room programme, the costs and the design of the pumping station.

Every ESC has available application forms for the establishment of the connected load, in which the required data such as the number and capacity of the individual consumers is entered.

5.2.1 Energy Supply with a Voltage up to 1000 V (Low Voltage)

Depending on local conditions there is a maximum possible connected load (standard value ca. 10 to 50 kVA) for the low voltage supply (LV supply) which depends on the respective ESC. Already for cost reasons an attempt should be made, as far as possible, to manage with a LV supply (in general 400/230 V AC), without limiting oneself operation-ally.

ATV-DVWK-A 134E

June 2000 29

Fig. 19: Basic forms for ready-built stations

5.2.2 Energy Supply with a Voltage over 1000 V (Medium High Voltage)

If the supply conditions do not allow a low voltage supply a medium high voltage supply is necessary. Medium high voltage switchboard plants are, in

any case, to be installed in locked operating rooms. For medium high voltage systems one or more transformers are required. Ready-made as-sembled small switchboard plants (compact plants) are available for smaller transformer capacities (see Fig. 19).

ATV-DVWK-A 134E

30 June 2000

The switchboard plants for voltage levels above 1000 V should, for the protection of personnel, be employed only as plants secured against accidental arcing in accordance with Pehla Directive No. 2, Criterion 1 to 6, with firmly installed switchgear or on a rail mounted platform (retractable).

In order that the switchgear still remains operable even with failure of the mains and the appropriate information is retained, it is recommended that both the drive of the switchgear and the control and reporting systems are designed independent of the mains supply (battery).

5.2.3 Measurement of Consumption

As a rule this is provided and installed by the ESC. The build-up of the metering facility depends on the voltage levels used and thus has an influence on the room programme. It is to be clarified with the ESC where the electricity consumption meter is to be installed.

5.3 Switchboard Plant, Actuators and Appliances

Low voltage switchboard plants are normally produced in the shape of standardised sheet steel cabinet systems which are secure against accidental arcing to increase the protection of personnel.

As a rule a modular method, otherwise an insertion method, is employed for the power items.

To control and monitor the machines motor control cards (electronic) can be used for the realisation of the basic circuitry and basic locking mechanism.

Higher voltage switches are realised through the employment of stored-programmable control systems (SPS).

Unavoidable blind current components should be compensated using fixed or regulatable blind current compensation. For later expansion a space and capacity reserve of from 15 – 20 % should be planned.

All switching plant is to be installed safe from flooding.

5.3.1 Main Drives

As far as possible, three phase squirrel-cage motors with small current at make should be provided as drive motors for the wastewater pumps (see Section 4.2.1).

Winding sensing devices can be planned to protect the motor against overload. For drives with operationally conditioned long down-times, and with high air humidity, a down-time heater can be practical.

The IP 54 system of protection is to be preferred.

Every drive has a control selection switch with the positions MANUAL – OFF – AUTOMATIC.

The switching ON and OFF of the pumps is dependent on water level, in special cases the delivery flow can be over or underlaid. Operating conditions must be recognisable on the electrical control panel. Pump exchange switch, current meter and operating hours counter should be integrated. In addition each drive has one (or more) EMERGENCY OFF switches in situ, which engage directly in the control system.

Faults always lead to the immediate shutdown of the plant. With this the control system, goes into locked status, an automatic restart following a fault may not occur.

Modification of the number of pump revolutions is possible through pole changing motors (2 or 3 rpm) or using frequency converter drives (infinitely variable, simultaneous starter in the lower rpm range).

Frequency converter drives create heat and noise which possibly has respectively to be dissipated or restrained. In addition, converters create harmonic waves in the power supply. The power supply reactions of these harmonic waves must be compensated.

ATV-DVWK-A 134E

June 2000 31

Attention is to be paid that the adjustment of the rpm modifies all characteristic curves of the pumps.

There are the following possibilities for the automatic operation of the pumps:

- Pumping control Conveyance of the pump is monitored.

- Protection against dry running It is prevented that the pump lowers the water level in the inlet chamber below a permitted level and thus runs dry.

- Simultaneous start Simultaneous start of large consumers is prevented to avoid expensive peak loads.

- Reserve pump with malfunction With malfunction of the service pump the reserve pump takes over operation automatically.

- Conveyed quantity- or pressure control - Parallel operation of several pumps - Reclosure preventing device

The immediate reclosure following switching off for operational reasons is prevented depending on time in order to avoid the inadmissible heating of electrical components and/or heavy start.

- Monitoring of oil and cooling water - Alternating closure

With every new closure impulse another drive is switched on in preselected sequence.

5.3.2 Ancillary Drives

Ancillary drives are, inter alia:

- Actuators for fittings, - Inlet chamber ventilators, if required pump

room ventilators, - Drainage pumps for pump rooms, - Booster pumps for wash down facilities, - Grease or oil pumps for bearing lubrication, - Lifting gear, - Compressors.

5.3.3 Ancillary Facilities

These cover:

- Electrical heating for frost protection, - Lighting plant, additional emergency lighting, - Battery systems,

- Plug connections for three phase 400 V to 63 A, 230 V/16 A AC and extra-low voltage 25 V/10 A,

- Water heaters for sanitary objects, - Connections for measuring technology, fused

outlets 230 V, - Reserve outlets; for each voltage level 1 to 3

reserve outlets.

5.3.4 Operating and Measuring System

Recording of operating and fault messages:

Operating messages should be displayed individually optically, fault messages shown individually optically and collectively acoustically. The fault messages can, if required, be combined together as a group fault message.

A test key for all illuminated displays is recommended.

The remote transmission of operating and fault messages as well as status signals can, for example take place via a cable or leased lines.

Remote transmission is, however, only sensible if there are possibilities of acceptance or of calling up this information in rotation as well as for its operational processing.

A telephone connection is necessary, alternatively paging or service radio. In any case personnel working in the pumping station must be available or must be capable of making contact with the control centre.

5.4 Emergency Power Supply

Depending on the security of the energy supply, possibilities of retaining the wastewater in cases of failure and the operational significance of the pumping station in the drainage system, a mobile or a stationary, automated emergency power equipment is required.

- Mobile plant This requires a signal of the fault at the central point, a possibility that the plant can be trans-ported in and connected to the switchboard plant rapidly and without complications, where-

ATV-DVWK-A 134E

32 June 2000

whereby, at the same time, the separation from the power supply and locking must take place.

- Automatic plant Automatic emergency power supply systems switch in immediately following voltage breakdown and, with a time delay, switch off following reestablishment of the power supply. For rotational maintenance their must be a possibility of running the emergency power system under load over several hours.

- Special cases The energy supply of the complete works or parts of this can take place with the aid of a stationary, automatic generator (see Section 4.2.2).

5.5 Types of Protection and Regulations

All equipment and installations must correspond with the relevant VDE and VBG regulations as well as the technical connection conditions (TAB) of the responsible ESC.

An earthing of the complete plant, incl. the conductive plant components which do not belong to the operating power circuit, in accordance with the VDE is to be carried out with the aid of the foundation earth planned by the customer and, if required, additional earthing (see Section 3.4.7).

Equipotential bonding between all conductive components must be carried out whereby protection against lightning strike is included in the bonding.

Lightning protection in accordance with ABB is required for superstructures (see Section 3.4.8).

5.5.1 Explosion Protection

With the pumping station, as a rule, the inlet chamber, inlet shaft and, possibly, the ventilator room are explosion endangered areas.

The operating equipment therein must be so installed and the plant so mounted and operated that no explosion can be caused.

Zones 0, 1 and 2 are differentiated according to the timely and local probability of the presence of dangerous atmospheres capable of explosion.

Valid as “explosion endangered rooms” are all rooms or areas in which, according to local or operational conditions, atmospheres capable of explosion can collect. In the area of the pumping station they are, in general, to be assigned to Zone 1, so that the Explosive Ordinance is to be applied.

5.5.2 Protection against Accidental Contact

In order to protect personnel working in a pumping station from the results of an electrical accident such as

- three-phase power accident, - arcing accident or - three-phase power accident with an intrinsically

non-hazardous current,

the following protection against accidental contact is necessary:

- protection with direct contact, - protection against direct contact, - partial protection against accidental contact, - protection with indirect contact.

Protective measures with indirect contact are fundamentally required with all electrical plant or equipment (see Section 3.4.7).

Protective measures without earth conductor:

- double insulation, - protective low voltage, - fuse.

Protective measures with earth conductor:

- protective earth, - earthing, - earthed conductor system, - fault-voltage [German = FU] protective circuit, - residual current [German = FI] operated

device.

ATV-DVWK-A 134E

June 2000 33

6 Measurement Engineering

The external prerequisites are practically identical with those of electrical engineering. The transmitters must, however, as a rule be install in situ. Therefore, with these devices there is the involvement of large expense for protection against moisture, cold, dust, corrosion through pollutants, mechanical damage as well as possibly for explosion protection.

With the employment of electronic components conditions are to be created which allow the electrical equipping of various type and design to exist alongside each other.

6.1 Level Measuring Systems

Level measuring systems are required for the determination of the respective water level on the inlet side and, in special cases, also on the outlet side and for the automatic control of the pumping plant.

The following measuring methods are employed:

- electrical pressure sensor, - depth sounder.

6.2 Delivery Pressure Measuring Systems

Delivery pressure measuring systems are required for the determination of the pressure head at the pump and the pressure in the pressure pipeline.

Electric pressure sensors, which are flanged directly to the pressure pipeline, are suitable for suction and pressure measurement. A further possibility lies in the employment of spring-tube manometers in overpressure secure design in accordance with DIN 16005 with a damping device and reinforced dial train as well as pure water seal.

6.3 Flow Measuring Systems

Permanently installed flow measuring systems are to be employed when a continuous measuring of the delivery flow is necessary for an accurate determination of the delivery efficiency of the pumping station. The manufacturer-specific installation conditions (e.g. calming stretches) are to be observed.

Magnetic-inductive flow measurement (MID) The measuring method functions without contact, therefore is reliable and easily maintained. The measuring system in addition is the only one capable of calibration.

Ultrasonic flow measurement Flow measurements with the aid of the Doppler effect are available. These systems are, however, significantly less accurate than the MID and not capable of calibration.

Flow monitoring In the area of wastewater flow monitoring is possible using the signals of the MID or from the position of the flap of the non-return valve.

6.4 Transmission of Measured Values

The electrical transmission of the measured values takes place via electronic measuring transducers which convert the measured value into a proportionally formed direct current of 0...20 mA or 4...20 mA and/or of 0...10 V.

7 Wastewater Pressure Pipelines

7.1 Pressure Pipelines

Pressure pipelines serve for the transport of the wastewater from the pumping station to the desti-nation. Pump and pressure pipeline are to be dealt with as hydraulic unit. The relationship is given, on

ATV-DVWK-A 134E

34 June 2000

one hand, by the pump characteristic curve (throt-tle curve) and the pipeline characteristic curve on the other (see Section 4.1.1).

The pressure pipeline must be able to accept the internal and external pressure on the system continuously and without damage. To this belong the pressure transient processes (e.g. water hammer), if no other safety measures are taken.

7.2 Pipeline Routes

Basically the pressure pipeline should represent the shortest possible connection between the pumping station and the discharge point.

The pipeline should as far as possible be laid straight constant with the run of the vertical position in order to keep the hydraulic losses low through small changes of direction. If the ground permits the pipeline should be designed with a steady incline in order to transport the air also conveyed to the end of the pipeline.

Digested matter in the wastewater can lead to the formation of H2S and thus to an endangering of the pipe inner walls. In particular the employment of cement-bonded materials (concrete pipes, cement-fibre and cement-mortar lining) is problematic here (see Advisory Leaflet ATV-M 168).

Pipelines must be laid at depths safe from frost or be appropriately protected. The required crown covering in Germany lies between 0.8 m and 1.5 m.

For static reasons (see ATV-A 127E) a greater minimum covering can be necessary in view of extreme traffic loading. Further security measures in the form of protective pipes or concrete cladding can be considered for use.

At significant high points pressure mains must equipped with venting and ventilation fittings.

Venting is necessary in order that the pipeline can be completely emptied and a return flow due to si-phoning effect is prevented. Ventilation is required for the controlled filling of the pipeline. With filled pipelines it is necessary to be able to remove en-

trained air or the gas cushions resulting from the formation of gas. Gas cushions can lead to higher energy losses as a result of a narrowing of the flow cross-section.

If, in the case of repair with pumps at standstill, the pipeline does not empty itself due to geodetic gradient, emptying pipelines with connection to the wastewater and combined wastewater sewer system or for suction vehicles are to be planned for suitable low points.

Monitoring ports, for example for pipe inspection using cameras, venting and ventilation as well as emptying fittings, are, from a practical point, to be accommodated in shafts which should be equipped with a pump well at the bottom.

7.3 Dimensioning

The required pipe diameter is determined based on the delivery flow determined through the hydraulic calculation (see Sections 2.6 and 2.7).

The pressure rating of the pipeline to be used is determined according to the static and dynamic effective internal pressure. Both the nominal width (DN) of the pipes and the pressure rating (PN) must correspond with DIN 2401 and DIN 2402 respectively.

The minimum and maximum speeds of the delivery flow are to be observed. Furthermore the statements in Section 2.7 apply.

As the delivery flow conditioned by the wastewater yield is subjected to considerable variations it can be practical, if required, to lay instead of one pressure pipeline a second (or more), which can, at the same time, serve as reserve pipeline. The pipe material is determined through the hydraulic, mechanical and chemical stresses which can have an effect both internal and external.

Pipe wall thickness is dependent on the required pressure rating, the external loads and the type of material.

The hydrostatic pressure is determined from the geodetic height difference. The dynamic loading results from the pressure loss and the unsteady

ATV-DVWK-A 134E

June 2000 35

pressure changes (pressure surges) combined through the individual pipe losses.

The overall dynamic pressure loss is made up from the pressure loss through pipe friction and the individual losses due to mountings, fittings such as, for example, elbows cross-section chambers and branches as well as through losses at inlets and outlets. For details see The ATV Handbook „Bau und Betrieb der Kanalisation“ [“Construction and operation of sewer systems]”.

7.4 Stresses

Pressure mains are subject to different stresses. They are caused by:

- transport and storage, - installation, - external forces, - internal forces, - temperature, - abrasion, - corrosion.

With the stresses through transport and storage, installation as well as through external forces a wastewater pressure main does not differ from drinking water pipelines. Important information can be found in EN 1610, DIN 4124 and DIN 19630.

With the internal forces attention is drawn particularly to stresses due to pressure surges. Pressure surges result following unsteady flow processes with the switching on and off of pumps, changes to the pump rpm or adjustment of gate valves and failure of pump drives. Physical bases and calculation procedures for pressure surges are contained in DVGW Advisory Leaflet W 303.

With wastewater pressure mains the pressure (water hammer) problem is reinforced in that the wastewater can form gases which combine in the high points into gas cushions. Pressure surges which occur in the presence of gas cushions are not predictable. Therefore the high points of wastewater pressure mains are to be inspected by rotation, even during operation, and if necessary vented.

With the exception of external temperature stresses against which a pipeline is to be protected

through minimum cover and/or insulation, with varying or even continuous high temperatures of the pumped medium, an additional stress of the pipeline can occur. The pipe material here is to be selected with particular care.

Abrasion occurs with pressure mains if increased mineral substances occur in the wastewater. Effects are to be expected particularly in the area of changes of direction and throttle points. It can be necessary to counter these through increasing wall thickness, for example through the selection of a higher nominal pressure rating, in the critical area.

7.5 Pipe Materials

The medium to be transported in wastewater pressure mains, as opposed to drinking water, cannot be described precisely. Wastewater can contain many putrefactive substances so that fresh and older wastewater in their behaviour with regard to some materials is different. Therefore, the selection of material is to be made taking into account local conditions. If required, appropriate pre-treatment and pipe protective measures are to be planned.

As materials there are available:

- metallic materials, - cement bonded materials, - ceramic materials and - plastic.

7.6 Corrosion and Corrosion Protection

Significant wastewater-specific attacks with wastewater pressure mains are, above all to be expected on the inner wall. With this the composition of the wastewater and its time-dependent possible change are of significance as well as the possible aggressiveness with partial (with gas formation in the crown areas) or complete filling of the pipeline.

Here it should be noted that wastewater pressure mains made from certain materials also have components such as fittings, seals and mountings made from other materials.

ATV-DVWK-A 134E

36 June 2000

Pipe materials susceptible to corrosion must be protected through internal and external insulation. Thus steel pipes receive externally a polyethylene jacket or coating with polyurethane tar and, internally, an epoxy-resin or cement mortar lining. With pressure pipes made from ductile cast irons external spray galvanisation, bitumen paint or epoxy-resin coating and internally cement mortar lining are used. Reinforced concrete and fibre-cement pipes in many cases receive an additional coating on a bitumen basis or of epoxy-resin (see DIN 4030), for example with the danger of sulphide formation in the wastewater and with high sulphate content.

8 Commissioning

The documentation of all plant components must be available for commissioning (see ATV-A 148E).

8.1 Pumping Station

Acceptance with functional testing and trial runs of the individual component parts must precede commissioning of the pumping station. Those responsible for planning and construction work, from the undertaking and, for reasons of warranty, also representatives of the manufacturer and/or supply companies are to take part in this.

Before commissioning the electrical plant all short circuit and overcurrent protective systems are to be checked for correct setting and are to be secure. All switching and control procedures are to be carried out first without loading (cold testing). Only then can the facility be released for operation.

In general the pumps have been subjected to a test bench trial at the manufacturer’s works. This factory acceptance serves for the examination of whether the guaranteed delivery data are achieved. In contrast to that the test run in the pumping station is to provide information on its mechanical and hydraulic behaviour, freedom from vibration, heating of bearings and correct function-ing of ancillary facilities (lubrication, cooling, venti-

lation, possibly regulation/control, displays) under the local installed conditions.

In detail the following are recommended as controls:

- tension-free assembly, - adjustment of end bearings and torque, - direction of pump rotation, - pump sequential switching, - setting of rpm, - venting of the pump casing, - sealing, - noises, - vibrations, - temperatures, - pressure surges, - non-return valve clapper knock, - measurement and control technology, - remote monitoring and control, - emergency energy supply.

The pumps should be tested under full load for at least two hours. If there is not enough water available for a test run it has proved advantageous if the existing water can be pumped via a diversion in a circle.

For the commissioning and later operation it is necessary that the operating personnel receive precise knowledge of the plant engineering already with assembly and that they have already received instruction.

The pumping station can be taken into operation after the functional testing.

With this the requirements of the pressure main commissioning are to be observed.

In the run-in phase (ca. 4 weeks) it is recommended that the complete operating cycle has increased monitoring as, from experience, an increased number of faults occur on the plant components during this period.

8.2 Pressure Main

An internal pressure test in accordance with DIN 4279 is to be undertaken before commis-sioning. For commissioning the ventilation fittings

ATV-DVWK-A 134E

June 2000 37

to be operated manually are to be opened and controlled during the filling procedure.

With the connection of the pressure main to the existing network with different pressure potentials, it should be noted that pressure surges result through too rapid opening or closing of the gate valves, which can lead to damage to the pressure main. Once a flow is no longer detectable the gate valve can be opened very slowly. Closure is carried out analogously.

Immediately after commissioning of a new pres-sure main the first pressure pipe characteristic curve should be adopted. It serves for the estab-lishment of a practical and economic dimensioning and for the evaluation of the delivery pumps in this pressure main.

9 Information on Stan- dard Specifications, Directives, Standards, Advisory Leaflets (Se- lection)

The documents listed below have been mentioned in this Standard and must be taken into account in the respectively valid version inter alia with the design and construction of a wastewater pumping station. [Translators note: Where there is a known official translation the title is given in English only. Otherwise a courtesy translation is given in square brackets after the German title.]

9.1 General Terms and Conditions for Engineering Services, (VOB)

Part C, General Technical Regulations for Engineering Services:

DIN 18 017 Part 1

Lüftung von Bädern und Spül-aborten ohne Außenfenster durch Schächte und Kanäle, ohne Motorkraft; Einzelschachtanlagen [Ventilation of baths and flush toilets without outer widows through shafts and channels, without motor drive, single shaft facilities]

DIN 18 300 Erdarbeiten [Excavation works] DIN 18 303 Verbauarbeiten [Revetting] DIN 18 304 Rammarbeiten [Pile driving] DIN 18 305 Wasserhaltungsarbeiten

[Dewatering works] DIN 18 306 Entwässerungskanalarbeiten

[Drainage sewer works] DIN 18 331 Beton und Stahlbetonarbeiten

[Concrete and reinforced concrete works]

DIN 18 335 Stahlbauarbeiten [Steel construction works]

DIN 18 336 Abdichtung gegen drückendes Wasser [Sealing against water under pressure]

DIN 18 363 Anstricharbeiten [Painting works] DIN 18 364 Korrosionsschutzarbeiten an Stahl-

und Aluminiumbauten [Corrosion protection works on steel and aluminium structures]

DIN 18 379 Lüftungstechnische Anlagen [Ventilation plants]

DIN 18 381 Gas-, Wasser- und Abwasserinstallationsarbeiten innerhalb von Gebäuden [Gas, water and wastewater installation works within buildings]

DIN 18 382 Elektrische Kabel- und Leitungsarbeiten in Gebäuden [Electrical cable and line works inside buildings]

9.2 Standard Specifications

DIN 4045 Wastewater engineering - Vocabulary

ATV-DVWK-A 134E

38 June 2000

EN 752 Parts 1-7

Drainage systems outside buil-dings

EN 1671 Pressure sewerage systems outside buildings

9.2.1 Building Standards

DIN 1045 Structural use of concrete; design and construction

DIN 1055 Parts 1- 6

Design loads for buildings

DIN 1084 Parts 1-3

Control (Quality control) of concrete structures and reinforced concrete structures

DIN 1164 Parts 1,2,8,

Portland-, Eisenportland-, Hoch-ofen- und Trasszement; Begriffe, Bestandteile, Anforderungen, Lieferung [Portland, iron Portland, blast furnace slag and trass cement; Terms, requirements, delivery]

DIN 1986 Site drainage systems DIN 1988 Drinking water supply systems DIN 2000 Zentrale Trinkwasserversorgung;

Leitsätze für Anforderungen an Trinkwasser, Planung, Bau und Betrieb der Anlagen [Central drinking water supply; Guidelines for requirements on drinking water, planning construction and operation of plants]

DIN 2001 Private and individual drinking water supply; governing principles

DIN 4030 Assessment of water, soil and gases for their aggressiveness to concrete

DIN 4124 Building pits and trenches – slopes, working place widths, sheeting

DIN 18 196 Soil classification for civil engineering purposes

9.2.2 Pipes and Fittings

DIN 1333 Zahlenangaben [Numerical data] DIN 2440 Steel tubes; medium-weight

suitable for screwing DIN 2448 Seamless steel pipes and tubes DIN 2458 Welded steel pipes and tubes DIN 2605 Parts 1-2

Steel butt-welded pipe fittings

DIN 2614 Cement mortar linings for ductile iron and steel pipes and fittings; application requirements and testing

DIN 3352 Parts 1-8

Gate valves [Available in English Parts 1-4 only]

DIN 4032 Concrete pipes and fittings DIN 4035 Stahlbetonrohre und zugehörige

Formstücke aus Stahlbeton [Reinforced concrete pipes and associated fittings made from reinforced concrete]

DIN 4279 Parts 1-10

Testing of pressure pipelines for water by internal pressure [Parts 1,7,8 not available in English]

DIN 8061 Unplasticised polyvinyl chloride pipes (PVC-U); general quality requirements and testing

DIN 8062 Unplasticised polyvinyl chloride pipes (PVC-U, PVC-HI); dimensions

DIN 8063 Parts 1-12

Pipe joints and fittings for pipes under pressure made of unplasticised polyvinyl chloride (PVC-U) [Parts 5,7,9,10 not available in English]

DIN 8074 Polyethylene (PE) pipes – dimensions

DIN 8075 Polyethylene (PE) pipes – dimensions – General quality requirements and testing

DIN 8077 Polypropylene (PP) pipes – dimensions

DIN 8078 Types 1, 2 and 3 Polypropylene (PP) pipes – General requirements and testing

DIN 14 365 Parts 1-2

Multi-purpose branch pipes for nominal pressure 16; dimensions materials, construction, marking

DIN 19 532 Rohrleitungen aus weichmacher-freiem Polyvinylchlorid (PVC hart, PVC-U) für die Trinkwasserversorgung [Pipelines made from unplasticised polyvinyl chloride [PVC-H, PVC-U for drinking water supply]

DIN 19 533 Pipelines of high density PE and low density PE for drinking water supply; pipes, pipe connections and fittings for pipelines

ATV-DVWK-A 134E

June 2000 39

DIN 19 534 Rohre und Formstücke aus weichmacherfreiem Polyvinylchlorid (PVC-U) mit Steckmuffe, für Abwasserkanäle und –leitungen [Pipelines and fittings made from unplasticised polyvinyl chloride (PVC-U) with sleeves, for drains and sewers]

DIN 19 537 High density polyethylene (HDPE) pipes and fittings for drains and sewers; technical delivery conditions

DIN 19630 Richtlinien für den Bau von Rohrleitungen [Directives for the construction of pipelines]

DIN 19 800 Part 1

Asbestos-cement pipes and fittings for pressure pipelines; pipes, dimensions

DIN 19 850 Parts 1-2

Fibre-cement pipes and fittings for drains and sewers; Part 1: dimensions of pipes, branches and bends; Part 2: Dimensions of joint assemblies

DIN 30 675 Parts 1-2

External corrosion protection of buried pipes, corrosion protection systems for steel and ductile iron pipes

EN 295 Vitrified clay pipes and fittings and pipe joints for drains and sewers

EN 545 Ductile iron pipes, fittings, accessories and their joints for water pipelines; Requirements and test methods

EN 639 Requirements for concrete pressure pipes including joints and fittings

EN 640 Reinforced concrete pressure pipes and distributed reinforce-ment concrete pressure pipes (non-cylinder type), including joints and fittings

EN 642 Prestressed concrete pressure pipes, cylinder and non-cylinder types, including joints, fittings and specific requirements for prestressing steel for pipes

EN 764 Pressure equipment; Terminology and symbols relating to tempe-rature, pressure and volume

EN 1032 Testing of mobile machinery in order to determine the whole body vibration emission value - General

EN 1299 Vibration isolation of machinery – information fort he application of source isolation

EN 1610 Construction and testing of drains and sewers

9.2.3 Mechanical Engineering

DIN 1184 Part 4

Pumping stations; Archimedean screw pumps; Directives for planning

DIN 1944 Acceptance tests on centrifugal pumps (VDI rules for centrifugal pumps)

DIN 24 260 Part 1

Kreiselpumpen und Kreiselpumpenanlagen; Begriffe, Formelzeichen, Einheiten [Centrifugal pumps and centrifugal pump systems; Terms, symbols, units]

DIN 24 293 Kreiselpumpen – Technische Unterlagen – Begriffe, Lieferumfang, Ausführung [Centrifugal pumps – technical documents, scope of delivery, design]

DIN 45 635 Part 1

Measurement of noise emitted by machinery

9.2.4 Measurement Technology

DIN 1319 Basic concepts in metrology DIN 16005 Überdruckmessgeräte mit

elastischem Messglied für die allg. Anwendung [Overpressure measurement equipment with elastic measuring unit for general applications]

EN 837-1 Pressure gauges - Part 1: Bourdon tube pressure gauges - dimensions, metrology, requirements and testing

EN 837-3 Pressure gauges – Part 3: Diaphragm and capsule pressure gauges; dimensions, metrology, requirements and testing

ATV-DVWK-A 134E

40 June 2000

VDE 0410 VDE-Bestimmung für elektrische Messgeräte; Sicherheitsbestimmung für anzeigende und schreibende Messgeräte und Zubehör [VDE regulations for electrical metering equipment; safety regulations for indicating and recording measuring equipment and accessories]

9.2.5 Electrical Engineering

VDE 0100 Bestimmungen für das Errichten von Starkstromanlagen mit Nennspannungen bis 1000 V [Regulations for the erection of high tension facilities with nominal voltages up to 1000 V

VDE 0105 Betrieb von Starkstromanlagen [Operation of high tension facilities]

as well as i.a.: EN 50110 Part 1

Operation of power installations

VDE 0160 Ausrüstung von Starkstromanlagen mit elektronischen Betriebsmitteln [Equipping of high tension facilities with electronic equipment]

as well as i.a.: EN 61 800 Part 3

Adjustable speed electrical power drive systems

VDE 0165 Errichten elektrischer Anlagen in explosionsgefährdeten Bereichen [Installation of electrical plant in explosion-endangered areas]

as well as i.a.: EN 60 079 Part 10

Elektrische Betriebsmittel für gasexplosionsgefährdete Bereiche [Electrical equipment for gas explosion endangered areas]

VDE 0170/0171

Elektrische Betriebsmittel für explosionsgefährdete Bereiche [Electrical equipment for explosion endangered areas]

As well as i.a.: DIN EN 50 014

Elektrische Betriebsmittel für explosionsgefährdete Bereiche; Allgemeine Bestimmungen [Electrical equipment for explosion endangered areas; General conditions]

DIN EN 50 015 Elektrische Betriebsmittel für ex-plosionsgefährdete Bereiche; Ölkapselung [Electrical equipment for explosion endangered areas; Oil immersion]

DIN EN 50 016 Elektrische Betriebsmittel für explosionsgefährdete Bereiche; Überdruck-kapselung [Electrical equipment for explosion endangered areas; Pressurising]

DIN EN 50 017 Elektrische Betriebsmittel für explosions-gefährdete Bereiche; Sandkapselung [Electrical equipment for explosion endangered areas; Powder filling]

DIN EN 50 018 Elektrische Betriebsmittel für explosionsgefährdete Bereiche; Druckfeste Kapselung [Electrical equipment for explosion endangered areas; Flame-proof enclosure]

DIN EN 50 019 Elektrische Betriebsmittel für ex-plosionsgefährdete Bereiche; erhöhte Sicherheit [Electrical equipment for explosion endangered areas; Increased safety]

DIN EN 50 020 Elektrische Betriebsmittel für ex-plosionsgefährdete Bereiche; Eigensicherheit [Electrical equipment for explosion endangered areas; Own safety]

DIN EN 50 021 Elektrische Betriebsmittel für ex-plosionsgefährdete Bereiche; Betriebsmittel der Zündschutzart [Electrical equipment for explosion endangered areas; Equipment with “e”-type protection ]

DIN EN 50 039 Elektrische Betriebsmittel für ex-plosionsgefährdete Bereiche; Eigensichere elektrische Systeme [Electrical equipment for explosion endangered areas; Intrinsically safe electrical systems]

DIN IEC 61024-1-2;

Blitzschutz baulicher Anlagen [Lightning protection of structural works]

VDE 0185 Part 102

ATV-DVWK-A 134E

June 2000 41

VDE 0266 Halogenfreie Kabel mit verbessertem Verhalten im Brandfall [Halogen-free cables with improved behaviour in case of fire]

VDE 0660 Niederspannungs-Schaltgeräte [Low voltage switch gear]

as well as i.a.: EN 60 439 Parts 1-5

Low voltage switchgear and control gear - combinations

EN 60 947 Parts 1-7

Low voltage switchgear and control gear

VDE 0670 Wechselstromschaltgeräte für Spannungen über 1 kV [AC equipment for voltages above 1 kV]

VDE 0800 Fernmeldetechnik [Telecommunications engineering]

9.3 Directives, Standards and Advisory Leaflets

9.3.1 of the ATV

ATV-A 105E Selection of the Drainage System ATV-A 110E Hydraulic Dimensioning and

Performance Verification of Sewers and Drains

ATV-A 116E Special Sewer Systems - Vacuum Drainage Service – Pressure Drainage Service

ATV-A 118E Hydraulic Dimensioning and Verification of Drainage Systems

ATV-A 127E Static Calculation of Drains and Sewers

ATV-A 128E Standards for the Dimensioning and Design of Stormwater Structures in Combined Sewers

ATV-A 142E Sewers and Drains in Water Catchment Areas

ATV-A 148E Service and Operating Instructions for Personnel of Wastewater Pumping Stations, Wastewater Pressure Pipelines and Stormwater Tanks

ATV-A 200E Principles for the Disposal of Wastewater in Rurally Structured Areas

ATV-A 241 Bauwerke der Kanalisation [Structures in Sewer Systems]

ATV-A 166 Bauwerke der zentralen Regenwasserbehandlung und -rückhaltung - Konstruktive Gestaltung und Ausrüstung [Structures for Centralised Treatment, Retention, Design and Equipping of Stormwater Facilities]

ATV-M 168E Corrosion of Wastewater Systems – Wastewater Discharge –

ATV-M 176 Hinweise und Beispiele zur konstruktiven Gestaltung und Ausrüstung von Bauwerke der zentralen Regenwasserbehandlung und -rückhaltung - [Notes and Examples for the Design and Equipping of Structures for Centralised Wastewater Treatment and Retention]

ATV-M 263E Recommendations for Corrosion Protection of Steel Components in Wastewater Treatment Plants Using Coating and Cladding

9.3.2 of the DVGW

DVGW W 302 Hydraulische Berechnung von Rohrleitungen und Rohrnetzen [Hydraulic calculation of pipelines and pipe networks]

DVGW W 303 Dynamische Druckänderungen in Wasserversorgungsanlagen [Dynamic pressure changes in water supply facilities]

DVGW W 342 Werkseitig hergestellte Zementmörtelauskleidungen für Guss- und Stahlrohre [Factory produced cement mortar cladding for cast and steel pipes]

DVGW W 345 Schutz des Trinkwassers in Wasserrohrnetzen vor Verunreinigung [Protection of drinking water from pollution]

9.3.3 des VDI

VDI 2058 Beurteilung von Arbeitslärm in der Nachbarschaft [Assessment of work noise in the neighbourhood]

ATV-DVWK-A 134E

42 June 2000

VDI 3743 Bl. 1 Sheet 1]

Emissionskennwerte technischer Schallquellen – Pumpen – Kreisel-pumpen [Characteristic values of emissions from technical noise sources – pumps - centrifugal pumps]

VDI 3803 Raumlufttechnische Anlagen Bauliche und technische Anforde-rungen [Ventilation and air conditioning facilities; structural and technical requirements]

9.3.4 of the VDMA [German Association of Mechanical Engineering Establishments]

VDMA 24 261 Part 1

Pumpen – Benennung nach Wir-kungsweise und konstruktiven Merkmalen – Kreiselpumpen [Pumps – designation according to functional and design characteristics – centrifugal pumps]

VDMA 24 297 Kreiselpumpen, Technische Anforderungen, Richtlinien [Centrifugal pumps, Technical requirements, directives]

10 Annexes

Annex 1: Example of a pumping station with centrifugal pumps in horizontal, dry-well installation

Annex 2: Basic circuit diagram