Advances in Water Treatment and Enviromental Management

PLANT MONITORING AND CONTROL SYSTEMS 95In summary, the needs assessment considered some 5600 in number sitesin steps of 20, 40 and 70% covering 70 installation types. The level ofprovision ranged from simple alarm monitoring to remote monitoring andcontrol across a mix of installation types. Against operational need thefollowing opportunities were assessed; reduced manpower and transportcosts, reduced electricity costs, improved asset management information,improved customer service and improved business managementinformation.DESIGN SOLUTION OPTIONSFollowing on from the needs analysis, three solution approaches werepursued:(a) do nothing(b) a manual solution(c) a technical solution.The ‘do nothing’ solution was rejected early in the project as the solutiondid not allow existing service levels to be maintained.The ‘manual’ solution assumed that all expenditure on existing telemetrywould cease and manpower would be employed to take over the functionsof the existing telemetry systems as and when these systems fail.The ‘technical’ solution involved the provision of telemetry, instrumentationand site wiring. To address the issue of scale and functionality the followingtechnical solutions were considered:(i) Like for like replacement.(ii) Simple alarm monitoring of some 20% of sites in each district.(iii) District based systems capable of a mixed sole functionality over arange 20, 40 and 70% of sites.(iv) Area based systems similar to (iii) but with the additional capability ofre-routing data between operational centres.(v) A regional system using shared equipment, organisational structureindependent and providing a central service to district managers.Within the business case methodology the emphasis on cost versus benefitsrequired that solutions were rigorously appraised with cost accuracies within10–15%.From experience of similar schemes, the PMCS project team realised thatsome 60–70% of the scheme cost would be committed to site related activities,viz. signals, communications, type of outstation. This being the very areawhere existing data was at its most incomplete.