SIST EN 12255-11:2023

Wastewater treatment plants - Part 11: General data required

This document specifies data which is necessary for the planning, design, bidding, performance guarantees, construction, start-up and compliance testing of a wastewater treatment plant or parts of it. This document gives fundamental information about the practices; this document has not attempted to specify all available practices.

Kläranlagen - Teil 11: Erforderliche allgemeine Angaben

Dieses Dokument legt allgemeine Grundlagen für die Planung, Auslegung, Angebotserstellung, Leistungsgarantien, Errichtung, Inbetriebnahme und Abnahmeprüfung von Kläranlagen oder Teilen von Kläranlagen fest. Die Unterschiede bei der Abwasserbehandlung in Europa haben zu einer Vielzahl von Verfahrensweisen geführt. Dieses Dokument enthält grundsätzliche Angaben zu den Verfahrensweisen; es legt jedoch nicht alle Einzelheiten jeder Verfahrensweise fest.

Stations d’épuration - Partie 11 : Informations générales exigées

Le présent document spécifie les données nécessaires pour la planification, la conception, la proposition, les garanties de performance, la construction, la mise en service et le contrôle de conformité d’une station d’épuration des eaux usées ou d’une partie de cette station. Le présent document donne des informations de base sur ces pratiques ; il n’est pas destiné à spécifier toutes les pratiques disponibles.

Čistilne naprave za odpadno vodo - 11. del: Zahtevani splošni podatki

Ta dokument določa podatke, ki so potrebni za načrtovanje, projektiranje, razpise, jamstva za pravilno izvedbo, gradnjo, zagon in preskušanje skladnosti čistilnih naprav za odpadno vodo ali njihovih delov. Zaradi različnih postopkov čiščenja odpadnih voda v Evropi so se razvile različne prakse. Ta dokument podaja osnovne informacije o teh praksah; namen dokumenta ni določiti vse razpoložljive prakse.

General Information

• Status: Published
• Public Enquiry End Date: 02-Sep-2021
• Publication Date: 10-Apr-2023
• ICS: 13.060.30 - Sewage water
• Technical Committee: IOVO - Water supply and waste water engineering
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 06-Apr-2023
• Due Date: 11-Jun-2023
• Completion Date: 11-Apr-2023
• Directive: 93/38/EEC - Procurement procedures of entities operating in the water, energy, transport and telecommunications sectors
• Mandate: M/BC/CEN/88/15 - Standardization request to CEN/CENELEC in the field of Water supply, drainage and sewerage
• Ref Project: EN 12255-11:2023 - Wastewater treatment plants - Part 11: General data required

Relations

• Replaces: SIST EN 12255-11:2001 - Wastewater treatment plants - Part 11: General data required
• Effective Date: 01-May-2023

Overview

EN 12255-11:2023 - Wastewater treatment plants: General data required (CEN) specifies the data and information needed for planning, designing, tendering, constructing, start-up and compliance testing of wastewater treatment plants (WWTPs) or parts thereof. It replaces EN 12255-11:2001 and forms part of the EN 12255 series covering general requirements and processes for municipal wastewater treatment plants (population equivalents > 50). This standard provides a consistent framework for clients, consulting engineers and contractors to define functional requirements, design loads and site constraints without prescribing specific technologies.

Key topics and technical requirements

• Contract strategy: Guidance on preparing a functional tender versus sectional tender and the role of consulting engineers and turn‑key contractors.
• Loading data provision: Required measured or estimated inputs including:
  • Sewerage system characteristics (combined/separate areas, storm storage, infiltration, flow control).
  • Population served (current, start-up, design working life, seasonal/weekly variations).
  • Significant trades and industries discharging to the sewer (COD, BOD5, TKN, NH4-N, NO3-N, phosphorus, TSS, salinity), with hourly, daily, weekly, annual and percentile metrics.
  • Data from existing WWTPs and design flows/loads.
• Effluent and residues: Effluent quality targets, storm overflow requirements, preliminary treatment residues and sludge disposal constraints.
• Site description: Plans, existing facilities, ground geology, groundwater, climate and special site constraints (including climate change impacts over the design working life).
• Start‑up and guarantee testing: Requirements for commissioning, performance guarantees and testing protocols.
• Operational costs & cost presentation: Framework for estimating construction and operational costs, and documentation required from designers or turn‑key suppliers.

Applications and who uses it

EN 12255-11:2023 is intended for:

• Municipalities and clients preparing tenders and defining performance requirements.
• Consulting engineers who determine design loads, prepare tender documents and supervise construction.
• Turn‑key contractors and equipment suppliers preparing proposals and guarantee tests.
• Contracting authorities and regulators assessing compliance, permits and environmental discharge limits. Practical uses include preparing functional tender documents, evaluating bids, sizing treatment units, defining monitoring and commissioning plans, and estimating life‑cycle costs.

Related standards

EN 12255-11 is part of the EN 12255 series (Parts 1–16) covering construction principles, preliminary treatment, primary/secondary/tertiary processes, sludge treatment, odour control, safety, control & automation, disinfection and more - useful cross‑references when applying EN 12255-11:2023.

Keywords: EN 12255-11:2023, wastewater treatment, general data required, design loads, effluent quality, sludge disposal, tendering, consulting engineer, turn‑key contractor.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2023
Nadomešča:
SIST EN 12255-11:2001
Čistilne naprave za odpadno vodo - 11. del: Zahtevani splošni podatki
Wastewater treatment plants - Part 11: General data required
Kläranlagen - Teil 11: Erforderliche allgemeine Angaben
Stations d’épuration - Partie 11 : Informations générales exigées
Ta slovenski standard je istoveten z: EN 12255-11:2023
ICS:
13.060.30 Odpadna voda Sewage water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 12255-11
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2023
EUROPÄISCHE NORM
ICS 13.060.30 Supersedes EN 12255-11:2001
English Version
Wastewater treatment plants - Part 11: General data
required
Stations d'épuration - Partie 11 : Informations Kläranlagen - Teil 11: Erforderliche allgemeine
générales exigées Angaben
This European Standard was approved by CEN on 2 January 2023.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12255-11:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and abbreviations . 7
5 Requirements . 7
5.1 Contract strategy . 7
5.2 Provision of loading data. 8
5.2.1 General . 8
5.2.2 Sewerage system . 8
5.2.3 Population served . 8
5.2.4 Significant trades and industries . 8
5.2.5 Data from existing wastewater treatment plants . 9
5.2.6 Design flows and loads . 10
5.3 Effluent quality, requirements for the disposal of residues and sludge . 10
5.3.1 Effluent quality . 10
5.3.2 Requirements for storm water overflow discharge . 10
5.3.3 Requirements for the residues from preliminary treatment . 11
5.3.4 Requirements for sludge disposal . 11
5.4 Site description . 11
5.4.1 General . 11
5.4.2 Plans (maps) of the site . 11
5.4.3 Existing wastewater treatment plants . 11
5.4.4 Ground geology, groundwater and climate . 12
5.4.5 Special site constraints . 12
5.5 Additional data required . 12
5.6 Time schedule . 13
5.7 Start-up and guarantee testing . 13
5.7.1 Start-up . 13
5.7.2 Guarantee testing . 14
5.8 Operational cost information . 14
5.9 Documents to be provided by a turn-key contractor or the consulting engineer . 14
5.9.1 Complete documents . 14
5.9.2 Design options . 14
5.9.3 Proposed solution . 14
5.10 Calculation and presentation of costs . 15
5.10.1 Construction costs . 15
5.10.2 Operational costs . 15
5.10.3 Presentation of costs . 17
Bibliography . 18

European foreword
This document (EN 12255-11:2023) has been prepared by Technical Committee CEN/TC 165 “Waste
water engineering”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2023, and conflicting national standards shall
be withdrawn at the latest by August 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 12255-11:2001.
This is the eleventh part of the EN 12255 series prepared by Working Group CEN/TC 165/WG 40,
relating to the general requirements and processes for treatment plants for a total number of
inhabitants and population equivalents (PT) over 50.
The EN 12255 series with the generic title “Wastewater treatment plants” consists of the following
parts:
— Part 1: General construction principles
— Part 2: Storm management systems
— Part 3: Preliminary treatment
— Part 4: Primary settlement
— Part 5: Lagooning processes
— Part 6: Activated sludge process
— Part 7: Biological fixed-film reactors
— Part 8: Sludge treatment and storage
— Part 9: Odour control and ventilation
— Part 10: Safety principles
— Part 11: General data required
— Part 12: Control and automation
— Part 13: Chemical treatment - Treatment of wastewater by precipitation/flocculation
— Part 14: Disinfection
— Part 15: Measurement of the oxygen transfer in clean water in aeration tanks of activated sludge
plants
— Part 16: Physical (mechanical) filtration
NOTE Part 2 is under preparation.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Introduction
Differences in wastewater treatment throughout Europe have led to a variety of systems being
developed. This document gives fundamental information about the systems; this document has not
attempted to specify all available systems. A generic arrangement of wastewater treatment plants is
illustrated below in Figure 1.

Key
1 preliminary treatment
2 primary treatment
3 secondary treatment
4 tertiary treatment
5 additional treatment (e.g. disinfection or removal of micropollutants)
6 sludge treatment
7 lagoons (as an alternative)
A raw wastewater
B effluent for re-use (e.g. irrigation)
C discharged effluent
D screenings and grit
E primary sludge
F secondary sludge
G tertiary sludge
H stabilised sludge
I digester gas
J returned water from dewatering
Figure 1 — Schematic diagram of wastewater treatment plants
The primary application is for wastewater treatment plants designed for the treatment of domestic and
municipal wastewater.
NOTE For requirements on pumping installations at wastewater treatment plants, see EN 752, Drain and
sewer systems outside buildings — Sewer system management and the EN 16932 series, Drain and sewer systems
outside buildings — Pumping systems:
— Part 1: General requirements;
— Part 2: Positive pressure systems;
— Part 3: Vacuum systems.
1 Scope
This document specifies data which is necessary for the planning, design, bidding, performance
guarantees, construction, start-up and compliance testing of a wastewater treatment plant or parts of it.
This document gives fundamental information about the practices; this document has not attempted to
specify all available practices.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
relevant plant
new wastewater treatment plant; rebuild, upgrade or extension of an existing wastewater treatment
plant or a part of a new or extended wastewater treatment plant (e.g. sludge handling facilities)
3.2
client
municipality, city or other organization which intends to build a wastewater treatment plant or parts
thereof, or its representative
[SOURCE: EN 12255-1:2002, 3.6]
3.3
functional tender
tender document that contains the design flows and loads, a description of the site where the relevant
plant is to be erected, the relevant discharge limits and any additional requirements
3.4
sectional tender
separate tender documents prepared for different sections of work that may be constructed by different
entities
Note 1 to entry: Examples of sections of work can include: earth work, concrete work, mechanical equipment,
electrical installations, buildings, etc.
3.5
consulting engineer
independent engineer or engineering company commissioned by the client designing a wastewater
treatment plant or parts of it and/or supervising the construction
Note 1 to entry: The consulting engineer may assist the client with any work preparing all or part of the tender
documents. The consulting engineer supervises the construction and checks the time schedule and costs. The
consulting engineer has knowledge and experience in planning, design and operational aspects of wastewater
treatment plants. In some countries, a special certification may be required.
3.6
turn-key contractor
builder who agrees to complete a facility so that it is ready for use when delivered to the other
contracting party
Note 1 to entry: The turn-key contractor is typically a company which has knowledge and experience in planning,
design, construction and operational aspects of wastewater treatment plants.
3.7
design working life
assumed period for which a structure or part of it is to be used for its intended purpose with anticipated
repair and maintenance but without renovation or replacement being necessary
Note 1 to entry: The "Design Working Life” can often be significantly longer than “design life” and is of critical
importance when calculating the longer-term resilience of drainage infrastructure, to, for example, climate change
impacts.
[SOURCE: EN 1990:2002, 1.5.2.8, modified to provide consistency with the terminology in EN 16323]
4 Symbols and abbreviations
COD chemical oxygen demand
BOD biochemical oxygen demand in 5 days
TKN total Kjeldahl nitrogen
NH -N ammonium-nitrogen
NO -N nitrate-nitrogen
COD/N ratio of COD and nitrogen
COD/P ratio of COD and phosphorus
5 Requirements
5.1 Contract strategy
The client may decide whether a functional tender or a sectional tender shall be prepared. The client
may commission a consulting engineer to carry out one or more of the following:
— establish the design loads and data as described in 5.2;
— prepare the tender documents for a functional tender;
— design the plant and estimate the costs and prepare the tender documents for the sectional tender;
— inspect the construction in case of functional tendering;
— supervise and coordinate the construction in case of sectional tendering;
— evaluate the bids on the tenders and to propose which contractor or contractors (in case of
sectional tendering) should be commissioned.
5.2 Provision of loading data
5.2.1 General
Where applicable the following basic data either measured or estimated shall be provided by the client
or his representative, e.g. consulting engineer.
5.2.2 Sewerage system
The data on the sewerage system should include:
— areas served by combined and/or separate sewers;
— proportions of flows and loads from separate and/or combined sewer systems in dry weather
conditions;
— storage capacity for storm water within the sewerage system and details of flow control systems;
— potential to control and balance flows and loads within the sewerage system;
— infiltration flows in dry weather conditions and their seasonal fluctuations (where appropriate);
— septic and corrosive components of the wastewater.
Dry weather conditions and fluctuations in storm water flow will be impacted by climate change. Local
interpretation of average and worst-case climate change scenarios over the design working life of the
sewerage system should be assessed to determine their potential impact.
5.2.3 Population served
The data on the population served shall include:
— current population connected to the sewerage system;
— population connected at start-up of the plant;
— population connected at design working life of the principal components and the design horizon for
the plant;
— seasonal variations of population (e.g. holiday periods);
— weekly variations of population (e.g. movement of commuting population).
5.2.4 Significant trades and industries
A list of trades and industries which discharge significant loads to the sewerage system should include
the following flows and loads, e.g.:
COD, BOD , TKN, NH -N, NO -N, total phosphorus, total suspended solids, organic suspended solids,
5 4 3
salinity and alkalinity; shown as current, start-up, and design target data for:
— hourly peak (m /h, kg/h);
— daily peak and daily average (m /d, kg/d);
— weekly peak day (m /d, kg/d);
...