UPM APPLICATIONS METHODOLOGY: FINAL REPORT
Report No FR0384

Jun 1993

SUMMARY

ACKNOWLEDGEMENTS

Some of the unattributed data and models used in the UPMAM modelling programme were provided by members of the Sewerage Management Planning Research Club (Anglian Water Services Ltd, North West Water Ltd, Severn Trent Water Ltd, Thames Water Utilities and Yorkshire Water Services Ltd) after the completion of a series of implementation of pilot studies.

I BENEFITS

Guidance on how to select appropriate models and optimise the outputs from the range of available UPM planning techniques for different applications will provide a major supporting input to the development of the UPM Manual.

II OBJECTIVES

To develop expertise for the practical application of the computer simulation models developed in the UPM programme to support the production of the forthcoming UPM Manual. This is to be achieved by the application of the full range of UPM planning techniques to a series of case studies, thereby:

1. Evaluating the performance (sensitivity and reliability) of individual component techniques/models;
2. Developing a practical approach for the integrated use of the complex UPM computer simulation models (MOSQITO, STOAT, MIKE 11) for sewerage pollution management; and
3. Evaluating the benefit of this approach (cost-savings and/or increased reliability/confidence in proposal schemes) against other planning techniques.

The original project objectives were revised with the agreement of the UPM Steering Committee to reflect developments and constraints in model and data availability. The range of conditions represented in the case study examples was more restricted than originally proposed.

III REASON

Numerous models and associated enabling procedures have been developed under the auspices of the UPM programme. To be of practical value to the Industry, guidance is required for the selection of the most appropriate models and procedures for different situations. Such guidance must effectively match the complexity, sophistication and costs (including data collection needs) of the modelling procedures to the nature and scale of the problems to be addressed. In addition, implementation procedures need to be fully developed and evaluated. Such procedures are required to underpin the development of the UPM Manual and provide interim advice pending its availability.

IV CONCLUSIONS

• UPMAM has enhanced the knowledge and understanding of the complex UPM models and how they should be used.
• The individual models, MOSQITO, STOAT and MIKE 11, were shown to produce usable results. The deficiencies identified in their ease of use were found to be commensurate with the complexity of the problems addressed by each model.
• STOAT was shown to require further expansion and software development.
• It was not possible to evaluate the scope for different levels of model accuracy, reflecting different levels of field data collection, because of the limited number of models and field data available. However, it was shown that predictions of dissolved oxygen levels in a river are highly sensitive to the model parameters, thus confirming the need for site specific data on dissolved oxygen response during storms.
• A "full" UPM modelling procedure was developed and shown to be practicable. The procedure involves creating simple derivative relationships, based on the complex model results, and then using these relationships in long (e.g. 10 year) simulations to de monstrate compliance with the intermittent standards.
• The "full" UPM modelling procedure was shown to produce more cost effective solutions than the simpler procedures in many situations.
• Some of the simpler procedures were shown to be potentially unreliable in situations of low river reaeration.
• The potential adverse impact of CSO upgrading upon sewage treatment works performance was shown to be considerable.

V RECOMMENDATIONS

• Environmental regulators should consider use of the "full" UPM modelling procedure where there is:
  • low dilution (less than 2:1 DWF : 5%ile river flow);
  • low reaeration potential; e.g. very slow flowing rivers, canals or significant ponding behind weirs;
  • concern about the effect of CSO upgrading on sewage treatment works performance.
• Operators should consider the use of the "full" UPM modelling procedure whenever the simpler planning techniques indicate costly solutions, as there may be the potential for cost savings.
• In planning applications, the detailed simulation models should be regarded as design tools. As such, uncertainty with regard to model accuracy or reliability should be handled by appropriate safety factors.
• The "full" UPM modelling procedure should be further developed and evaluated for the UPM Manual.
• Further studies should be carried out to support the implementation of the UPM Manual in areas not addressed under UPMAM, such as data collection effectiveness, model accuracy and model reliability.

Vl RESUME OF REPORT

Sections 1 and 2 of this final report describe the background to the project and the development of circumstances and end-user requirements which necessitated the revision of the project objectives. Section 3 presents the models used and the results from individual component models as applied to 5 case studies. Section 4 describes and compares the case study solutions based on the use of MOSQITO, STOAT and MIKE 11 with those from traditional approaches or the interim UPM planning procedures (CARP, SRM II). Section 5 develops guidelines for using the UPM models and Section 6 assesses practical constraints associated with currently available model versions. Project conclusions and recommendations are presented in Section 7. Detailed case study model descriptions and modelling results can be found in Appendix A and Appendix B respectively.

Copies of the Report are available from FWR, price £35.00 less 20% to FWR Members