Phase three
Managing discolouration

Introduction

The PODDS model, developed by the Pennine Water Group at the University of Sheffield has been shown capable of predicting the discolouration response of distribution networks to changes in hydraulic conditions. Results highlighting the capabilities of the full model are presented in figure 1 (below). The model is based on the novel application of cohesive transport theory and its development has led to a step change in philosophy and perception relating to discolouration.

The PODDS II research project developed the model into a tool suitable to be readily utilised by the water industry and the confidence in the parameter dataset required to achieve accurate model simulations. Critically the second phase suggested differential rates of material accumulation (layer regeneration or asset deterioration) within water distribution networks based on water quality factors and how hydraulic regimes may limit the overall accumulated material. Additional confirmation of these findings and how this information may be best utilised, including the application to larger diameter trunk mains now remains to be resolved.

The third phase of this project is therefore a way for the collaborators to lead the industry in developing and producing justifiable guidelines for planning operational and maintenance strategies to manage discolouration.

Project objectives

PODDS III aims to:

• Quantify the relative influence of different possible controlling factors on material accumulation and subsequent mobilisation processes within plastic potable water distribution systems pipes, under controlled conditions.

• Undertake field based regeneration trials to validate and further the findings of the idealised laboratory conditions, including other pipe materials.

• Develop a PODDS parameter dataset such that material mobilisation predictions can be made for transmission (trunk main) pipe systems.

Project approach

1. Controlled laboratory testing

Initial trails have been conducted in a pipe loop facility (non-temperature controlled) confirming that material layers can be accumulated and subsequent discolouration generated in a laboratory based pipe loop. Issues remain over the practical applicability of these results as the system operated at 20°C and hence the biological processes involved may be considered non-representative.

It is proposed to conduct trials utilising a new temperature controlled pipe test loop facility at the University of Sheffield. This is an internationally unique facility, with the capability of fully recreating operational pressures and flows and time vary patterns within a controlled environment. The rig is comprised of 79mm internal diameter MDPE pipe, representative of pipe currently installed in the UK. The rig will comprise ~600m of pipe, which can be run either as a complete length or as three independent systems.

The control of a laboratory facility will be used to systematically investigate and quantify the relative impact of different potentially influencing factors and mechanisms on material accumulation rates. Only by testing influencing processes in isolation can a true appreciation of their significance be derived.

Questions that it is proposed to investigate include:

Hydraulics

• Is there a steady state self cleaning velocity?

• What are the effects of daily flow patterns? Does this change if a stagnation period is present?

• Is there an ultimate layer strength for plastic pipes?

Source water effects

• What is the effect of changing concentrations of iron, manganese and aluminium (the dominant metals species found consistently in flushing samples)?

• What is the effect of pH, alkalinity, DO?

Infrastructure

• What would be the influence of introducing a length of cast iron pipe into the system?

The laboratory based studies will run throughout the programme, with details of further study to be refined on an ongoing basis through the steering group and with reference to the field results.

2. Field regeneration trials

Field sites utilised during PODDS II will continue to be tested in the same manner at determined intervals. This will provide quantification of regeneration processes within live water distribution systems, capturing the complex interaction of processes and variables at each site. This data will provide:

• Confidence in the repeatability of regeneration processes in sites where conditions do not change.

• Verification of the effects quantified through idealised laboratory trials by comparison between the different sites and with respect to changes to these sites.

3. Trunk mains

Due to the criticality and political sensitivity of trunk mains, any work proposed relating to trunk mains will be subject to change and adaptation to suit individual company policies and strategies. However, due to significant level of interest, current uncertainty and need for practical tools relating to discolouration in trunk mains as expressed by the PODDS II Water Company Consortium, it is proposed to attempt development of the PODDS approach for prediction of trunk main response to changing hydraulic conditions. This will be conducted on a site by site basis as opportunities arise within the companies of the consortia.

Journal and conference papers

Husband, S, Williams, R, Boxall, J B (2009)
Risk managed trunk main operation – abstract. Third IWA Leading-Edge Conference on Strategic Asset Management (LESAM09).

Husband, S, Whitehead, J, Boxall, J B (2009)
Long term trunk main monitoring yields operational dividends – abstract. Third Biennial Conference of the UK Network on Potable Water Treatment and Supply.

Husband, S, Whitehead, J, Boxall, J B (2009)
The role of trunk mains in discolouration. Under submission.

Husband, S, Boxall, J B (2008)
Asset deterioration rates and discolouration risk in water distribution systems – abstract. Editing prior to submission.

Husband, S, Boxall, J B (2008)
Field studies of discolouration in water distribution systems: model verification and practical implications. Journal of Environmental Engineering – submitted.

Husband, S, Boxall, J B, Saul, A J (2008)
Laboratory studies investigating the processes leading to discolouration in water distribution networks. Water Research – in press.

Vreeburg, J H G and J B Boxall (2007)
Discolouration in potable water distribution systems: a review. Water Research 41, pp. 519–529.

Husband, P S and J B Boxall (2008)
Water distribution system asset deterioration and impact on water quality: a case study. World Environmental and Water Resources Congress 2008, Ahupua'a, Hawaii, ASCE.

Husband, S, Boxall, J B (2007)
Repeat DMA flushing operations: discolouration comparison, modelling and management – abstract. Proceedings of the EPSRC Developments in Water Treatment and Supply, 4–5 July 2007, Bath, UK.

Boxall, J B and Prince, R A (2006)
Modelling discolouration in a Melbourne (Australia) potable water distribution system. Journal of Water Supply: Research and Technology – AQUA, IWA. 55.3, pp. 207–219.

Husband, S, Boxall, J B (2005)
Material accumulation and mobilisation in a pipe loop system. Proceedings of the EPSRC Developments in Water Treatment and Supply, 5–6 July 2005, York, UK.

Boxall, J B and Saul, A J (2005)
Modelling discolouration in potable water distribution systems. Journal Environmental Engineering ASCE, vol. 131, no. 5.

Boxall, J B, Saul, A J and Skipworth, P J (2004)
Modelling for hydraulic capacity. Journal of the American Water Works Association, vol. 96, no. 4, pp. 161–169.

Boxall, J B, Skipworth, P J and Saul, A J (2003)
Aggressive flushing for discolouration event mitigation in water distribution networks. Water Science and Technology – Water Supply, vol. 3, part 1/2, pp. 179–186.

Boxall, J B, Unwin, D M, Husband, P S, Saul, A J, Dewis, N and Gunstead, J D (2003)
Water quality in distribution systems: rehabilitation and maintenance strategies. Proceedings of the International CCWI conference, Advances in Water Supply Management, 15–17 September 2003, Imperial College London, UK.

Boxall, J B, Dewis, N (2003)
Identification of discolouration risk through simplified modelling. Journal Environmental Engineering ASCE, EWRI 2005.

Boxall, J B, Saul, A J, Gunstead, J D and Dewis, N (2003)
Regeneration of discolouration in distribution systems. Proceedings of the ASCE, EWRI, World Water and Environmental Resources conference, 23–26 June 2003, Philadelphia, USA.

Seth, A, Bachmann, R T, Boxall, J B, Saul, A J and Edyvean, R (2003)
Characterisation of materials causing discolouration in potable water systems. Water Science and Technology, vol. 49, no. 2, pp. 27–32.

Boxall, J B, Skipworth, P J and Saul, A J (2001)
A novel approach to describing sediment movement in distribution mains, based on measured particle characteristics. Proceedings of the International CCWI conference, 3–5 September 2001, De Montfort University, UK.

Project base

• University of Sheffield

• Department of Civil Engineering

• Pennine Water Group

Project collaborators

All of the project sponsors below provided operational experience, field sites and assistance.

• Northumbrian Water

• Seven Trent Water

• Southern Water

• United Utilities

• Wessex Water

• Yorkshire Water

PODDS IV

PODDS IV proposal

PODDS III Seminar

A pdf version of the presentations from the PODDS III seminar, Cropston Water (STW) on 9 November 2009. PowerPoint files can be accessed from here.

As part of the Seminar proceedings the users guide to the PODDS Model and Epanet Manual (2009) was updated.

Reports (chronological order)

PODDS III final report

Transfer report – laboratory investigations into processes causing discoloured potable water. A report presenting data from a temperature controlled test loop facility at the University of Sheffield written by Rebecca Sharpe as part of her doctoral research program.

Trunk main cleaning project undertaken by Northumbrian Water on their Southern Trunk Main used a PODDS concept approach with flow increases based on predictive modelling using parameters transferred directly from those obtained from Severn Trent Water Strelley trunk main. Early data from hydroclams and using actual flow data clearly supports the PODDS approach and the diligence of NWL in achieving the required flow increases. PODDS modelling of this data using the transferred parameters highlights the potential of PODDS in maintaining the integrity of these critical components of water distribution systems.

CCWI conference, Sheffield 2009 – copy of the paper and presentation by Jan Vreeburg (KWR) titled 'Origin and behaviour of particles in drinking water transport networks' in which he presents the theory of turbophoresis, the movement of particles from high turbulent to low turbulent zones that could help explain the development of material layers. The paper also presents data from flushing of two trunk mains, used to support this theory. The data however demonstrates classic PODDS material mobilisation and this has been roughly modelled using standard parameters and data presented in the paper. Further data required to complete modelling.

YW Rivelin trunk main – addition of regeneration rate to modelling second (of three) flow trial, October 2009.

STW Strelley trunk main sampling report, October 2009.

NWL DMA Pine Hills regeneration report, September 2009.

WW Bowden trunk main flow trial, September 2009.

YW Rivelin trunk main third trial, July 2009.

UU DeeLDTM report and OMC, June 2009.

YW Rivelin trunk main report and OMC, June 2009.

PODDS III mid project summary, February 2009.

Regeneration of discolouration material, Wessex Water, Poole DMA, June 2008 and January 2009.

Turbidity results Southern Water, Minster DMA, February 2009 (repeat visit).

Turbidity results Southern Water, Crawley DMA, February 2009 (repeat visit).

Turbidity results Wessex Water, Poole DMA, January 2009 (repeat visit).

Trunk main flushing and PODDS modelling report Severn Trent Water, Strelley, October 2008.

Regeneration of discolouration material in two United Utilities DMAs after cleaning of the Dee LDTM.

Turbidity results United Utilities, Rainhill DMA, September 2008 (second repeat visit).

Turbidity results United Utilities, Frodsham DMA, July 2008 (second repeat visit).

Turbidity results Northumbrian Water, Pine Hills DMA, July 2008.

Hydraclam analysis United Utilities Heswall trunk main, June 2008.

Turbidity results Yorkshire Water, Bradford DMA, June 2008.

Turbidity results Wessex Water, Poole DMA, June 2008.

Turbidity results Northumbrian Water, Seaham DMA, June 2008 (second repeat visit).

Turbidity results Severn Trent Water, Rykneld Road DMA, March 2008 (repeat visit).

Turbidity results Southern Water, Minster DMA, March 2008.

Turbidity results Southern Water, Crawley DMA, March 2008.

PODDS modelling report for Severn Trent Water / SEAMS, Codnor 12" CI, June 2007.

Supporting documents

PODDS III planned schedule (high-level Gantt).

PODDS III DMA investigation protocol for site selection and requirements.

PODDS III trunk main protocol for site selection and requirements.

PODDS III laboratory pipe rig explanatory and proposal document.

Steering group meetings

Inaugural meeting 10 December 2007, University of Sheffield: agenda, presentation, minutes.

Second meeting 3 April 2008, University of Sheffield: agenda, presentation, minutes.

Third meeting 8 July 2008, University of Sheffield: agenda, presentation, minutes. In addition there were slides submitted by Northumbrian Water with results from fieldwork comparing colour card data to the PODDS discolouration risk analysis tool – NWL DRAT results.

Fourth meeting 7 October 2008, University of Sheffield: agenda, presentation, minutes. In addition there were slides submitted by United Utilities and their use of Optimatics Optiflusher to design and trial a flushing programme (pending), slides from NWL comparing DRAT to colour card data and slides from SW (Atkins) and their flushing programme and field equipment.

Fifth meeting 13 January 2009, University of Sheffield: agenda, presentation, minutes. In addition there were updated DRAT analysis slides submitted from NWL comparing DRAT to colour card data initially shown in the fourth meeting.

Sixth meeting 21 April 2009, University of Sheffield: agenda, presentation, minutes.

Seventh meeting 21 July 2009, University of Sheffield: agenda, presentation, minutes.

Eighth and final meeting 19 July 2009, University of Sheffield: agenda, presentation, minutes.

Risk tool

Discolouration risk analysis tool – opens a folder with the latest version, Epanet.exe file, Epanet.dll file and two example Epanet files. These can be downloaded and saved as appropriate. Instructions for use can be found in the user manual.

Discolouration risk analysis tool user manual – methodology, operation and validation document.

Publications

S Husband, J B Boxall (2010)
Field studies to inform the management of discolouration risk in water distribution systems. Submitted to Water Research.

S Husband, R Williams, J B Boxall (2010)
Risk managed trunk main operation. Abstract submitted to WDSA 2010.

P Dienes, R Sekar, S Husband, J B Boxall, A M Osborn and C A Biggs (2010)
A new coupon design for simultaneous analysis of in situ microbial biofilm formation and community structure in drinking water distribution systems. In press, Applied Microbiology and Biotechnology.

S Husband, J Whitehead, J B Boxall (2010)
The role of trunk mains in discolouration. In press, Journal of Water Management, ICE.

S Husband, J B Boxall (2010)
Field studies of discolouration in water distribution systems: model verification and practical implications. Journal of Environmental Engineering 136 (1), pp. 86–94.

A Seth, S Husband, J B Boxall (2009)
Rivelin trunk main flow test. Proceedings of the 10th International Conference on Computing and Control for the Water Industry (CCWI) 1–3 September, Sheffield, UK.

S Husband, J Whitehead, J B Boxall (2009)
Long term trunk main monitoring yields operational dividends. Third Biennial Conference of the UK Network on Potable Water Treatment and Supply, Buxton, 1–2 June 2009.

S Husband, J B Boxall, A J Saul (2008)
Laboratory studies investigating the processes leading to discolouration in water distribution networks. Water Research 42 (16), pp. 4309–4318.

P S Husband and J B Boxall (2008)
Water distribution system asset deterioration and impact on water quality - a case study. ASCE World Environmental and Water Resources Congress, May 13-16, Ahupua'a, Hawaii, USA

J H G Vreeburg and J B Boxall (2007)
Discolouration in potable water distribution systems: a review. Water Research 41, pp. 519–529.

S Husband, J B Boxall (2007)
Repeat DMA flushing operations: discolouration comparison, modelling and management. Proceedings of the EPSRC Developments in Water Treatment and Supply, 4–5 July 2007, Bath, UK.

J B Boxall and R A Prince (2006)
Modelling discolouration in a Melbourne (Australia) potable water distribution system. Journal of Water Supply: Research and Technology – AQUA, IWA. 55.3, pp. 207–219.

S Husband, J B Boxall (2005)
Material accumulation and mobilisation in a pipe loop system. Proceedings of the EPSRC Developments in Water Treatment and Supply, 5–6 July 2005, York, UK.

J B Boxall, N Dewis (2005)
Identification of discolouration risk through simplified modelling. Proceedings of the ASCE, EWRI, World Water and Environmental Resources Congress, 15–19 May, Anchorage, Alaska, USA.

J B Boxall and A J Saul (2005)
Modelling discolouration in potable water distribution systems. Journal Environmental Engineering ASCE, vol. 131, no. 5, pp. 716–725.

J B Boxall, A J Saul and P J Skipworth (2004)
Modelling for hydraulic capacity. Journal of the American Water Works Association, vol. 96, no. 4, pp. 161–169.

J B Boxall, P J Skipworth and A J Saul (2003)
Aggressive flushing for discolouration event mitigation in water distribution networks. Water Science and Technology – Water Supply, vol. 3, part 1/2, pp. 179–186.

J B Boxall, D M Unwin, P S Husband, A J Saul, N Dewis and J D Gunstead (2003)
Water quality in distribution systems: rehabilitation and maintenance strategies. Proceedings of the International CCWI conference, Advances in Water Supply Management, 15–17 September 2003, Imperial College London, UK.

J B Boxall, A J Saul, J D Gunstead and N Dewis (2003)
Regeneration of discolouration in distribution systems. Proceedings of the ASCE, EWRI, World Water and Environmental Resources Conference, 23–26 June 2003, Philadelphia, USA.

A Seth, R T Bachmann, J B Boxall, A J Saul and R Edyvean (2003)
Characterisation of materials causing discolouration in potable water systems. Water Science and Technology, vol. 49, no. 2, 27–32.

J B Boxall, P J Skipworth and A J Saul (2001)
A novel approach to modelling sediment movement in distribution mains based on particle characteristics. Water Software Systems, vol. 1: Theory and Applications (Water Engineering & Management). B Ulanicki, B Coulbeck and J P Rance, Research Studies Press, Hertfordshire, UK, pp. 263–273.

Other documents

Contacts list, last updated March 2008.