UPM River Reaches
The InfoWorks ICM UPM (Urban Pollution Management) module provides facilities for the management of wastewater discharges from urban sewerage systems under wet weather conditions. The module allows you to enter details of environmental standards and make an assessment of whether these standards are met. The results of simulations are used to check that the pollutant levels from sewer outfalls and treatment works are at satisfactory levels. If not, the applicable network model can be modified and the results re-assessed.
Details of the standards to be applied and the recommended modelling procedure are given in the UPM Manual. The manual includes a simple spreadsheet (SIMPOL), which has been adopted as the standard tool for conducting UPM studies. The InfoWorks ICM UPM module follows the procedures used in SIMPOL and produces its results in the same format.
The UPM procedure typically involves running up to 40 years of rainfall through a sewer network model and calculating total spill volumes for each event at each CSO (combined sewer outfall). Spill loads are calculated at a user-defined timestep (usually 1 or 6 hours). Volumes and pollutant loads at time of maximum spill volume are tabulated.
River flows and concentrations, and treatment works discharges to the river are generated statistically from a log normal distribution using means and variances defined in a UPM river data item. If you want to calculate the change in dissolved oxygen and BOD downstream of the discharge, additional parameters for use in the decay equations and for describing downstream flow geometry must also be entered.
The UPM procedures are used to calculate total BOD and ammonia concentrations, as well as un-ionised ammonia and dissolved oxygen concentrations. A table is produced showing the number of times selected pollutant thresholds have been exceeded. These thresholds define the durations for which certain concentrations can be tolerated (for a given return period) and the acceptable levels of concentrations.
Generating a UPM river impact assessment involves three stages:
- Enter information relating to the river reach that is being assessed. (See UPM River Data.)
- Specify the thresholds against which the levels of pollutants in the water are to be tested. (See UPM Thresholds.)
- Generate a report containing the spills table and river impact assessment table. (See UPM River Impact Assessment.)
For details of the equations used in generating the assessment, see UPM Theory.
