Denver Water's Phased Approach to Achieving an All-Pipes Water Quality Model

Abstract

Denver Water (DW) serves over 1.1 million customers and supplies about 500 million gallons per day on a maximum day basis. The DW system includes three treatment plants, 17 major pump stations and over 160 pressure zones with over 400 pressure reducing valves. DW's primary responsibility is to supply high quality water to its customers at the lowest cost possible. This paper will present the process and results of a three-phased approach DW used to complete a suite of distribution system models, ultimately geared to meet the Stage II DBPR as well as provide guidance to operations for effective energy management. In 1997 DW began a process of creating steady state and extended period simulation (EPS) transmission models for a comprehensive Capital Improvement Program (CIP). This CIP planning was completed in late 2000. The transmission model was expanded in a second phase by creating a steady state all-pipes model in 2002. This more detailed model allows hydraulic analysis of smaller distribution mains. The third phase of the modeling transformed the steady state model into an all-pipes EPS model. This last model was calibrated using two system-wide tracer tests at maximum day and fall average day conditions. The all-pipes EPS model allowed accurate determination of detention times within the distribution system as well as determining efficient water quality sampling locations to meet regulatory requirements. The EPS model was also used to refine operational energy requirements.