Sewerage

Ref: 22/SW/01/23            Price: £10

ISBN: 978-1-84057-957-4

Infiltration detection in sewers

Whilst there are several available methods, infiltration continues to be a significant problem in sewers for water utilities. This report establishes the current position of the industry on the efficiency and reliability of existing methods, and to explore whether there are any methods in testing which might show promise on a wider scale.  

This UKWIR project was led by Arcadis

The project was primarily a data collection exercise with three strands of research:

• Practitioner Questionnaires: Questionnaires were sent out to industry practitioners to collate information from those with direct experience of one or more detection methods.
• Internal UK Research: This consisted of a critical review of information available online and from within the water engineering business of Arcadis UK.
• Internal International Research: This consisted of a review of past projects from within the Arcadis Global business, plus collecting information through Arcadis global Communities of Practice.

Ref: 22/WW/02/15            Price: £10

ISBN: 978-1-84057-948-2

Diffuse pollution such as urban run-off and atmospheric deposition is a well-established source of pollutants. This project reviewed existing data and knowledge of chemicals of emerging concern (CEC) in urban run-off (including highways) and atmospheric deposition and assessed the potential for this data to be used within the Source Apportionment Geographical Information System (SAGIS) modelling system.

This UKWIR project led by Atkins with the University of Plymouth presents the current understanding through:

• providing a systematic review of relevant literature to identify contributions of a defined range of CECs and microplastics and to identify possible knowledge gaps.
• evaluating sources to assess their potential to inform an update of data included in SAGIS, as well as to identify information gaps.
• reviewing interventions for the interception of microplastics and the identified CECs during their transit from source to receptor.

Ref: 22/SW/01/22            Price: £10

ISBN: 978-1-84057-947-5

Groundwater infiltration in urban drainage systems is costly to the water industry, impacting on system performance and operating costs. Loss of effective system capacity increases the risk of level of Service failures including flooding and environmental pollution. Infiltration flows may represent over 50% of inflows to wastewater treatment works adding to treatment costs and increasing wastewater spills to the environment   

This UKWIR project led by Stantec, supported by HR Wallingford aimed to develop an understanding Ground Infiltration modelling. The key objectives of the project were:

• To obtain a better understanding of slow response runoff and groundwater infiltration.
• To develop a greater understanding of infiltration tools, relating them to physical processes, so that models which are calibrated may be used with greater confidence.
• To bring greater consistency, accuracy and transparency to the approach to infiltration modelling by providing good practice guidance for the water industry to follow.

Ref: 20/SW/01/20            Price: £10

ISBN: 978-1-84057-911-6

Managing and removing surface water from sewers offers a number of operational benefits. Using different types of sustainable interventions can create substantial wider community benefits.

There is an increasing appetite across the industry to consider and deliver such interventions to help manage a range of drivers. However, this appetite is not matched by an in depth understanding of the factors that make surface water removal options more cost beneficial than traditional engineering solutions.

This UKWIR project led by Stantec, CIRIA and Anthony McCloy Associates helps to develop that understanding through:

• providing examples of surface water removal projects from the UK and Ireland and globally
• identifying the factors which make surface water management solutions successful
• understanding some of the UK and Ireland legislation that effects the delivery of surface water interventions
• developing a decision support tool to help those undertaking surface water removal projects in making better decisions

Ref: 19/SW/03/1            Price: £10

ISBN: 978-1-84057-884-3

The opportunity for heat recovery from sewers and other forms of energy generation was investigated and a selection tool produced to identify heat recovery opportunities and support water utilities in developing clear business cases.

The literature review identified the scale of energy recovery technologies available to water services utilities.

Risks from blockages caused by heat exchanger or turbine heat recovery in the sewerage system were identified as were potential risks to wastewater nitrification (unless heat is taken from treated effluent).

The legal conclusion reached is that wastewater may be classified as waste, therefore permits may be required. 

Heat recovery from wastewater can make a significant contribution to the reduction of the carbon footprints in water utility service providers. The scale and opportunity for energy recovery from sewers is dependent on local conditions.

Ref: 19/SW/01/19            Price: £10

ISBN: 978-1-84057-868-3

The overall aim was to model solid transport and deposition of sediment in urban sewerage systems as a means to investigate the possible impact of water conservation measures taken in the home on the self cleansing ability of a sewerage network.

Ref: 18/SW/01/18            Price: £10

ISBN: 1 84057 859 9

Sewer blockages due to discharges of fats, oils and greases (FOG) can cause flooding and pollution events. These events are unpleasant for the public, can cause property and environmental damage and can result in the Water and Sewerage Companies (WaSCs) receiving a fine. Further to this, Outcome Delivery Incentives (ODIs) have been set within the water companies in England and Wales to financially motivate, using penalties and rewards, lower occurrences of sewer flooding events (amongst other categories). Through detailed interviews with UK WaSCs, it was found that 13-31% of blockages in the UK are attributed to FOG, that uncertainties lie around WaSC legislative powers, and that the education and enforcement approaches differ. These interviews and the comprehensive literature review and interviews with global water utilities, local authorities and FOG collection/recycling solution providers gave insight into the various approaches employed across the world to control FOG discharges, and the opportunities for FOG collection and recovery in the UK. The FOG strategy, developed as part of this project clearly sets out the path to collect and recover all FOG by 2030, and achieve zero uncontrolled FOG discharges from sewers by 2050.

Ref: 16/SW/01/16            Price: £10

ISBN: 1 84057 820 3

Collaborative working between water and sewerage companies is in its infancy and there is therefore a need to develop common and systematic approaches to:

- identify and prioritise collaborative funding opportunities;
- work together to identify the full set of costs and benefits to different partners;
- ensure that partnership working can save money, unlock investment, and deliver multiple benefits;
- apportion benefits of investment to each partner and hence indicate a potential funding contribution, and;
- consider appropriate delivery mechanisms, and how to manage financial and delivery risks.

Guiding principles developed for this project build upon the existing good practice and will support a common and systematic approach to unlock collaborative opportunities. 

This report is available free of charge from the Environment Agency's website.

Ref: 16/SW/01/15            Price: £10

ISBN: 1 84057 806 8

This study identifies and quantifies the features of the various Planned Preventative Maintenance (PPM) approaches for managing the 350,000 blockages that occurring in the UK each year. The effective management of blockages first required the characteristics to be understood and this included demonstrating they are not random events. The use of Multiple Factor Analysis identified both static and time varying blockage correlations factors to explain the non-randomness, and this provided the ability to target PPM activities or explain performance changes. The use of SewerBatt to repeatable survey 50 sewers over a 6 month period showed blockages form when a set of circumstances occur following cyclical process of accumulation and erosion. The financial and non-financial features of the most common PPM approaches were quantified and the economic analysis completed, with the results being presented in an Intervention Hierarchy.The outputs from the study have been used to formulate a series of recommendations to improve the management of sewer blockages.

Ref: 15/SW/02/2            Price: £10

ISBN: 1 84057 785 1

It is said that 90% of utility visits to manholes are to rehabilitate the manhole cover. This report includes research into two common double-triangular manhole cover failure modes: settlement of covers within their frames and polishing of the profiled cover surface.

The hypothesis that manhole cover settlement is directly related to load flexing is investigated through the correlation between finite element analysis of load flexing and the settlement measured at the corners of 278 in-service covers.

The mechanism by which cover profiles are worn down is described, and a standard test method is presented for accelerated simulation of this wear.

An apparatus and standard method for testing the skid resistance of manhole covers is also described. This will enable the development and specification of highly skid-resistant manhole covers, making travel safer for motorcyclists.

Ref: 15/SW/01/12            Price: £10

ISBN: 184057 773 8

Wastewater systems have traditionally been fit-and-forget; however, long-term-pressures of increased needs and reduced budgets combine to require a new approach. Integrating the monitoring, modelling and management of wastewater systems to drive Active System Management (ASM) can help to deliver improved performance at less cost.

This report sets out a vision for how wastewater systems could be actively monitored, modelled and managed by, say, 2025. It reviews the gap from current practice to this vision and identifies what actions are required to fill the gaps, including what technology developments are required.

ASM does not have to be complex nor expensive it is a tool that can be implemented to support management from very simple situations through to highly complex ones. 

The report sets out options, from simple to complex, for:
  How the operator or control system knows what is happening
  How actions are taken to manage the system.

Ref: 15/SW/01/11            Price: £10

ISBN: 184057 772 X

Many sewerage catchments in the UK suffer infiltration problems when groundwater levels rise. Groundwater enters sewers though various means including underground leaks and can overload a network, giving rise to sewer flooding and unusable sanitation. Mitigation approaches such as tankering or over-pumping to watercourses can be expensive and/or unpopular with local residents.

The industry frequently addresses infiltration by sealing assets against ingress, but this may not be the most economic approach, particularly where mitigation (such as prevention of inflows from other sources) is possible. This report describes and assesses options for the prevention, management and mitigation of infiltration, taking account of water company experience, stakeholder views and published literature.

A framework has been developed for the economic assessment of intervention options, and its use is demonstrated through application to two case studies. To support this framework, methodologies are proposed to estimate in advance the costs and benefits of an intervention. In addition, an approach has been developed to model the relationship between rainfall and infiltration-related sewer flooding. Where successful, this could be used to distinguish weather-related changes in performance from those that are due to infiltration prevention measures, to enable the benefits of these measures to be quantified following implementation.

Ref: 15/SW/01/10            Price: £10

ISBN: 184057 761 4

This project provides an extensive study on the consequences for the Water Industry of widespread market penetration of food waste disposers (FWDs). It aims to improve the understanding of the potential consequences that FWDs may have on Water Industry assets and to help and inform Water and Sewerage Companies (WaSCs) in future discussions with relevant stakeholders responsible for waste disposal strategy.

The report outlines the potential impact on wastewater operations arising from widespread FWD use. The broad conclusion is that widespread penetration of FWDs would have an adverse impact on WaSC operations, customers and the environment.

Ref: 15/SW/01/14            Price: £10

ISBN: 1 84057 789 4

This report gives details of an extensive review of bio-additive dosing into sewer systems, both to degrade and control FOG deposits. The project showed that dosing can be successful, provided that the product is effective, site characteristics are considered and suitable site related practices are carried out.
To help promote successful dosing, a two stage protocol is specified, as follows:

- A testing methodology, to demonstrate a products ability to digest/degrade FOG (lipolitic activity); and 
- Site related aspects a methodology for planning, initial dosing to remove accumulated FOG deposits and maintenance dosing to minimise future FOG depositions.

This report has 2 sub reports, both downloadable free of charge. To access the documents please click the following links:

Part 1 - Laboratory Testing of Bio-Additive Dosing Compounds

Part 2 - Catchment, Site and Deployment Related Aspects - Summary Report

Ref: 15/SW/01/13            Price: £10

ISBN: 1 84057 787 8

This report and associated appendices provides a comprehensive review on FOG enabling Water and Sewerage Companies (WaSCs) to develop their strategy in the short, median and long term for dealing with FOG. A technical tool, which can be used to aid strategy development, utilising the quantities of FOG discharged by different producers has been developed.

An economic framework is also presented which will enable economic business cases to be developed. WaSCs can, utilising both models, develop the most appropriate strategy for dealing with FOG.

The authors engaged with key stakeholders from WaSCs along with representatives from a number of other organisations such as Local Authorities, Hospitality and Food Services sector and FOG Processors.

Ref: 14/SW/01/9            Price: £10

ISBN: 1 84057 727 4

This report and associated appendices provide a comprehensive review of data requirements for all below ground assets and pumping stations, to ensure service delivery in sewerage systems. Good practice guidance for the collection, storage and management of data is presented, including a conceptual data model Entity Relationship Diagram and a comprehensive list of data items. An economic framework is also presented which will enable economic business cases to be developed to demonstrate the long term benefits of appropriate data collection that can be understood and supported by regulators, customers and other stakeholders. The project and report are based on consultation with different water industry data stakeholders including asset managers, operations managers, contractors and customer services.

Ref: 14/SW/01/7            Price: £10

ISBN: 1 84057 723 1

This guide explains the basis for the UKWIR runoff model and the data requirements for its use. It explains the application of the model and suggested limits for its application. In addition, the issue of flow data collection to achieve models that are fit for purpose is also discussed.
The UKWIR study from which this guide was one of the deliverables involved the development and testing of a revised urban runoff model to replace the New PR runoff equation, to address a number of concerns within the water industry. A full report on the development of the Model is also available (14/SW/01/6).

Ref: 14/SW/01/6            Price: £10

ISBN: 1 84057 722 3

The study involved the development and testing of a revised urban runoff model to replace the NEW PR runoff equation, to address a number of concerns within the water industry. The study considered the possibility of using a range of alternative models, but in the end a major revision of the New PR equation was carried out. The analysis compared the proposed (UKWIR) equation with both the Old PR and New PR equations as well as ReFH to check predictions for the pervious runoff component. The revised model incorporates the ability to use HOST soil classes as well as the traditional WRAP soil classes, and it also separates out the runoff components of paved and pervious surfaces. The model was checked against a number of verified Infoworks models. A separate element of the study looked into developing an alternative approach to modelling catchments which suffer from excessive infiltration using Artificial Neural Network (ANN) techniques.
This report is the full study report and includes the software and user guide (14/SW/01/7).

Ref: 14/SW/01/8            Price: £10

ISBN: 1 84057 721 5

This report provides a framework for water utilities seeking to make a positive business case for catchment-wide stormwater management programmes. The approach is consistent with the requirements of the Drainage Strategy Framework and is applicable in all UK jurisdictions. The research is based on literature review and on consultation with those direcly involved in drainage planning as well as other interested parties.
The report recommends that water and sewerage companies work collaboratively with partners to test the benefits of stormwater management programmes as an effective response to climate change, urban creep and population growth pressures. Adopting as standard practice the UK specific tools currently being developed (in other research through CIRIA) to quantify benefits from sustainable drainage techniques is also recommended, so that our understanding of the balance between costs and benefits of stormwater management can be improved.

Ref: 13/SW/01/4            Price: £10

ISBN: 1 84057 700 2

This project report summarises the work carried out to produce an industry guide on Active System Control (ASC) for sewerage. The project considered the current usage of ASC in the UK, where it was felt that insufficient consideration of the use of ASC was being made, and also investigated its application elsewhere in the world. The report uses the term ˜Active System Control"in preference to the alternative ˜Real Time Control" (RTC) to avoid excluding schemes where decisions and interventions are not made instantaneously.

The study has also delivered a Guide which is aimed at supporting the UK water industry with particular emphasis on development of robust schemes, and how they should be evaluated. The Environment Agency and Ofwat have provided supportive position statements with regards to the use of ASC schemes for sewerage systems. The Guide makes use of anecdotal information to emphasise various aspects, such as involvement of the operations section in developing scheme concepts and operating control systems.

It is intended that this study and the Guide will lead to greater consideration and use of ASC for sewerage in the UK.

The Guide (13/SW/01/5) may be purchased alone for £200, or, together with this background Project Report (13/SW/01/4), for £300.

Ref: 13/SW/01/3            Price: £10

ISBN: 1 84057 670 7

For the last sixty years, separate sewers have been provided for foul wastewater and surface water. Unfortunately, over time, the separation of the flow has become compromised because of misconnections by third parties.
The project aimed to determine the true scale of such misconnections, the options for identification and control and, where possible, the environmental impact of polluted surface water sewer outfalls.
The available data has been analysed and it has been concluded that, on a UK wide basis, around 13 million properties are served by separate sewer systems of which around 1% are likely to be misconnected. A targeted programme to identify these properties, concentrating on areas where surface water outfalls are having an adverse environmental impact, is estimated to cost £190 million.

Ref: 12/SW/01/2            Price: £10

ISBN: 1 84057 656 1

HR Wallingford led a consortium of 5 contractors on behalf of UKWIR to carry out an investigation into the use of ANN models (Artificial Neural Networks) for producing 'instant' predictions of the performance of sewerage systems in real time.
An ANN model is trained against a series of recorded events for a point of interest (eg CSO spills and rainfall), and then used to predict its performance during current conditions.
The outcome of the project indicated that these models could achieve high levels of accuracy.
This tool is seen as being of value to the operations sections of water companies in providing rapid, continuous predictions during a rainfall event. This would allow instant intervention to be taken if a network incident is indicated.
The next stage for testing these models would be to carry out a field trial.

Ref: 12/SW/01/1            Price: £10

ISBN: 1 84057 653 7

The project objective was to prove the concept of having a decision support tool(s) that enables the financial comparison to be made between removing infiltration from the sewer network and continuing to accept the flows, at a catchment-wide level. The tool was developed in two parts; technical and economic. The technical tool has been developed using a risk based methodology within InfoNet Software WHICH IS NECESSARY TO RUN THE TOOL. It assesses the pipe integrity and groundwater availability at every pipe in the sewer network and then distributes the 'Unaccounted for Flows' across the network according to these risk values. This enables identification of feasible intervention strategies that can be priced using the sconomic tool. The economic tool is based on monetary value and carbon footprint of alternative strategies. It calculates the Net Present Value, allowing direct comparisons. The tools developed have successfully proved the concept and provided the industry with an innovative method for future assessment of strategic infiltration scenarios.

Ref: 11/WM/07/15            Price: £10

ISBN: 1 84057 584 0

Over the next 5 years, the UK Water Industry will be obliged to adopt thousands of privately owned pumping stations. It is important that the industry should adopt a co-ordinated approach so that the Sewerage Undertakers can establish a capital programme that is acceptable to Ofwat.
The UK Sewerage Undertakers have been consulted and an acceptable minimum level of serviceability has been recommended for adopted pumping stations. This will ensure that the transferred asset is safe, reliable and maintainable.
The guidance given in this report can be used as a starting point when identifying improvements needed before adoption and will aid the development of a costed transfer programme.
An Excel spreadsheet tool has been developed in conjunction with this report to simplify and tabulate the process.

Ref: 10/WM/07/14            Price: £10

ISBN: 1 84057 558 1

Urban Creep is the loss of permeable surfaces within urban areas creating increased runoff which contributes to flooding and other problems.
This was the first large scale study in the UK and high resolution aerial imagery from two periods for five sample locations (Leicester, Maidstone, Chester, Norwich and Newcastle-Upon-Tyne) was used with each sample area covering 100 sq km. Advanced processing technology was used to identify changes in paved and roof areas. This technique was particularly successful in identifying changes in rear gardens which in previous studies was not accessible.
In total over 34,900 samples were analysed, equating to about 2 million properties, and it was found that the average rates of urban creep were between 0.4 and 1.1 sq m/house/year depending on the city. A sophisticated statistical analysis of multiple variables was undertaken and the results enable modellers to predict the urban creep and increases in flooding for years ahead.

Ref: 09/WM/07/13            Price: £10

ISBN: 1 84057 533 6

Urbanisation and climate change are increasing the volume of rainfall discharging to the public combined sewerage system, resulting in increased risk of flooding and pollution with unnecessary pumping and treatment costs.
This project investigated the potential solutions for taking out surface water from existing combined sewerage systems, identifying the criteria that produce both positive and negative cost benefits to stakeholders, through initially a desk top exercise followed by the development of a simple spreadsheet 'Decision Support Tool' to assist the industry, and the application of pilot studies to confirm the outputs of the research.

Ref: 08/WM/07/12            Price: £10

ISBN: 1 84057 485 2

UK sewerage systems have changed little in the last 100 years in terms of their principles, materials and methods of installation and maintenance. However the pressures on the systems have increased enormously and the ways in which the service is managed, financed and regulated have changed greatly. Increasing environmental awareness, climate change and the drive for continuous improvement in efficiency and service all demand that the systems must adapt to meet future needs. This project seeks to identify the actions that the UK water industry must take to ensure that the sewerage infrastrucure and the service it provides will meet the needs of the 21st Century. The report is published in four volumes covering data collection together with operations and management, active control of sewerage systems, lifestyle and environmental factors and finally, legal and regulatory issues. An Executive Summary brings together the many conclusions and recommendations of the project and is provided free of charge with this volume four report.

Ref: 08/WM/07/11            Price: £10

ISBN: 1 84057 484 4

UK sewerage systems have changed little in the last 100 years in terms of their principles, materials and methods of installation and maintenance. However the pressures on the systems have increased enormously and the ways in which the service is managed, financed and regulated have changed greatly. Increasing environmental awareness, climate change and the drive for continuous improvement in efficiency and service all demand that the systems must adapt to meet future needs. This project seeks to identify the actions that the UK water industry must take to ensure that the sewerage infrastrucure and the service it provides will meet the needs of the 21st Century. The report is published in four volumes covering data collection together with operations and management, active control of sewerage systems, lifestyle and environmental factors and finally, legal and regulatory issues. An Executive Summary brings together the many conclusions and recommendations of the project and is provided free of charge with this volume three report.

Ref: 08/WM/07/10            Price: £10

ISBN: 1 84057 483 6

UK sewerage systems have changed little in the last 100 years in terms of their principles, materials and methods of installation and maintenance. However the pressures on the systems have increased enormously and the ways in which the service is managed, financed and regulated have changed greatly. Increasing environmental awareness, climate change and the drive for continuous improvement in efficiency and service all demand that the systems must adapt to meet future needs. This project seeks to identify the actions that the UK water industry must take to ensure that the sewerage infrastrucure and the service it provides will meet the needs of the 21st Century. The report is published in four volumes covering data collection together with operations and management, active control of sewerage systems, lifestyle and environmental factors and finally, legal and regulatory issues. An Executive Summary brings together the many conclusions and recommendations of the project and is provided free of charge with this volume two report.

Ref: 08/WM/07/9            Price: £10

ISBN: 1 84057 482 8

UK sewerage systems have changed little in the last 100 years in terms of their principles, materials and methods of installation and maintenance. However the pressures on the systems have increased enormously and the ways in which the service is managed, financed and regulated have changed greatly. Increasing environmental awareness, climate change and the drive for continuous improvement in efficiency and service all demand that the systems must adapt to meet future needs. This project seeks to identify the actions that the UK water industry must take to ensure that the sewerage infrastructure and the service it provides will meet the needs of the 21st Century. The report is published in four volumes covering data collection together with operations and management, active control of sewerage systems, lifestyle and environmental factors and finally, legal and regulatory issues. An Executive Summary brings together the many conclusions and recommendations of the project and is provided free of charge with this volume one report.

Ref: 08/WM/07/8            Price: £10

ISBN: 1 84057 481 X

UK sewerage systems have changed little in the last 100 years in terms of their principles, materials and methods of installation and maintenance. However the pressures on the systems have increased enormously and the ways in which the service is managed, financed and regulated have changed greatly. Increasing environmental awareness, climate change and the drive for continuous improvement in efficiency and service all demand that the systems must adapt to meet future needs. This project seeks to identify the actions that the UK water industry must take to ensure that the sewerage infrastrucure and the service it provides will meet the needs of the 21st Century. The report is published in four volumes covering data collection together with operations and management, active control of sewerage systems, lifestyle and environmental factors and finally, legal and regulatory issues. This Executive Summary brings together the many conclusions and recommendations of the project.

Ref: 06/WM/07/6            Price: £10

ISBN: 1 84057 426 7

UK sewer systems have developed over the last 150 years, to protect public health and provide adequate drainage. The value of existing systems has recently been estimated at £115bn. This project examined the future for UK sewerage systems up to 2080. Potential socio-economic and climate change drivers, over short and long time scales, were examined. This highlighted the need to change current practice in a number of areas. Recommendations were made as to the new approaches and tools required to provide flexible and adaptable responses, in order to make sewerage systems more resilient and capable to cope with future change.

Ref: 97/WM/07/1            Price: £10

ISBN: 1 84057 002 4

The number of pumped detention storage tanks built has rapidly increased in the last five years and the operational practices of the Water Companies varies widely. There is a wide range of design criteria and maintenance practice used for off-line pumped storage tanks, yet there is limited official design documentation.

The primary operations activity is related to pump maintenance and little is known about the performance of many of the tanks since telemetry is rarely used. The criteria used on the Continent resulting in the practice of building large tanks for environmental protection is now being questioned by many academics and practitioners.

Ref: 00/WM/07/4            Price: £10

ISBN: 1 84057 220 5

This report assesses the extent of rats in sewers in UK, and the effectiveness of current eradication procedures being used by the water utilities. An examination of design, construction and maintenance of sewers, together with likely future changes in sewer systems is made with a view to minimising rodent presence, minimising damage and assisting control. The study utilises results from a study of sewer rate behaviour in an experimental sewer rig, and sewer baiting trials to support the findings. Cost effective service indicators are proposed to control rat populations in sewers to acceptable levels.

Ref: 97/WM/07/2            Price: £10

ISBN: 1 84057 004 0

Provides information on the types of anti-flooding devices available, gives guidance on the situations in which they are appropriate and discusses data reliability and maintenance aspects. Reports the effectiveness of such devices based on the analysis of an industry questionnaire. Discusses the implications of a draft European standard.