REQUIREMENT SPECIFICATION FOR MOSQITO 2: ENHANCEMENTS TO THE CAPABILITIES OF THE MOSQITO 1 VERSION OF A SEWER FLOW QUALITY MODEL
Report No FR0032

Apr 1989

SUMMARY

I OBJECTIVES

To assess the requirement for enhancements to the capabilities of the current sewer flow quality simulation model (MOSQITO 1) and to produce a Requirement Specification for an upgraded model to incorporate identified enhancements.

II REASON

To initiate the next stage in MOSQITO development to meet the sewer quality modelling capability requirements of the Industry in the early 1990's.

III CONCLUSIONS

MOSQITO 2 should redress the deficiencies recognised in the original model and include the further capabilities required by the Industry. The enhancements will be limited by the nature and extent of available data. A new Requirement Specification has been produced which reflects an assessment of priorities compatible with existing data collection programmes and available databases for the period 1990-1992.

IV RECOMMENDATIONS

MOSQITO 2 should:

1. include improved calibration to make the best use of available data;
2. incorporate the results of ongoing research and data collection programmes to improve the modelling of the behaviour of sediments and sediment associated pollutants within the sewerage system; and
3. improve the modelling of the behaviour of sediments in ancillary structures.

In addition, the parameter modelling capability should be increased to include:

1. a simple stochastic model to simulate the discharge of bacterial indicator species; i.e. Total (Presumptive) Coliforms, Faecal (Thermotolerant) Coliforms and Faecal Streptocci.
2. hydrogen sulphide generation, based on existing models.

Initial development of a deterministic model for bacterial indicator species should be commenced with currently available data.

Heavy metals associated with storm sewage discharges are not considered to be of major significance except under particular local circumstances. Hence, the inclusion of a modelling capability for heavy metals in MOSQITO is not recommended at this stage

In addition to existing ongoing data collection programmes, it is strongly recommended that further data collection should be undertaken to allow effective testing and verification of MOSQITO 2 for use in both combined and separate drainage systems prior to release.

Further fundamental research should be commenced in the near future to facilitate enhancements beyond those considered in this report.

V RESUME OF CONTENTS

Section 1 outlines the limitations of MOSQITO 1. Section 2 discusses the background to the Requirement Specification for the next stage of model development, MOSQITO 2, which is presented in Section 3. The original Requirement Specification for MOSQITO 1 is presented in Appendix 1.

Copies of the Report are available from FWR, price £15.00 less 20% to FWR Members