Advances in Water Treatment and Enviromental Management

OPTIMISING PUMPING PLANT OPERATION 113FIG. 12 SIMPLIFIED NETWORK [STUDY 2]study were firstly to reduce pumping costs by scheduling and secondly to reduce abstractionat PS1 by pumping from PS3. This station had been little used for a number of years; integratingits operation with that of PS1, coupled with recent pipe modifications at R1, considerablyincreased the scope for pump scheduling in this system. Under certain circumstances thewater quality of one of the sources at PS1 limited the useable pump combinations available atthis station.PUMPLAN showed that by capitalising on the increased pumping capacity now that PS3 wasavailable and by scheduling both stations, a 14% reduction in the current annual pumpingenergy cost of over £400,000 could be achieved. At the same time abstraction rates at PS1were reduced to a satisfactory level.The schedules for PS1 and PS2, Figs.13 and 14, show that reduced pumping has been achievedbetween 07:00 hrs and 19:00 hrs when both peak rates and maximum demand chargesapply. Some increase in pumping is necessary between 19:00 and 24:00 hrs to prevent reservoirlevels dropping below the desired start level for the following day; although peak rate electricityis being used, the effect on pumping cost is not as serious as it would have been had theadditional pump been switched on during the maximum demand period. The correspondingreservoir profiles are shown in Fig. 15 and reflect the changes in pumping combinationthroughout the day.5 PUMP SCHEDULING—THE FUTUREThe privatisation of the water industry and new legislation are creating a need for continuedimprovement in the efficiency and reliability of water supply system operation and also inwater quality. These improvements will necessitate more sophisticated control of the day today operation of supply systems; it is in the operational decision support role that schedulingprograms will become increasingly important.