WATER MASTER PLAN OPTIMIZATION ALLOWS NORTH PENN WATER AUTHORITY TO EVALUATE ALL OF ITS OPTIONS

摘要

North Penn Water Authority (NPWA), located in Bucks and Montgomery Counties,Pennsylvania, serves roughly 27,000 customers. NPWA oversees a system with435 miles of water mains. The distribution system includes five pressure zones thatreceive water from 23 production well sources and a surface water treatment plant tomeet an average daily demand of about nine million gallons (MG). Other facilities withinthe distribution system include seven water storage tanks and five booster pumpingstations.NPWA and CH2M HILL in conjunction with Optimatics, conducted a master-planningproject that included the development of hydraulic and water quality models andoptimization using genetic algorithms (GAs) to support the development of a costefficientand defensible Capital Improvement Plan (CIP). This master-planning approachwas utilized to consider a wide range of improvement options to meet future demandconditions while obtaining the most cost-effective and hydraulically efficient plan.The careful construction of the master plan was important to NPWA in order toadequately serve a fully developed service area by the Year 2030. This service areagrowth and development is projected to increase the existing average daily water demandfrom approximately 9 MG to 13 MG under full buildout conditions, with maximum daydemands reaching 19 MG.After constructing the calibrated hydraulic model, a modeling analysis was performed toidentify deficiencies in the existing system and deficiencies that would be caused byincreased future demand. Upon identifying deficiencies, NPWA worked with CH2MHILL and Optimatics to identify all possible solutions to the identified deficiencies. Thisresulted in approximately 315 existing pipe alignments that could be relined or upsized,175 possible new pipe alignments, 8 potential new tank locations, 2 new booster stationlocations and 7 pressure zone boundary adjustments. Additionally, each of theseimprovement options was given a range of possible sizes. This wide range of variablesresulted in a very complex analysis, obviously beyond the capabilities of a trial and errorapproach.The system improvements were optimized to meet established hydraulic performancecriteria and minimize both operating and capital costs. The capital improvement projectsidentified and optimized by the GA analysis were confirmed by NPWA to be feasible anddesirable improvements. After this confirmation, the optimized improvements werephased over a 25-year planning horizon to comprise a fully optimized CIP.