Water System Master Plan and Hydraulic Model Update

Public Water Supply District No. 2 of St. Charles County

Horner & Shifrin prepared a Water System Master Plan for the largest water district in the State of Missouri.


Horner & Shifrin was responsible for the preparation of a Water System Master Plan for the largest water district in the State of Missouri serving a population of 100,000 people and over 400 square miles, which contains 10 different water systems, the Main Water Systems and nine small remote systems.  The Main Water System consists of 5 wells, 14 storage tanks, 9 booster stations, and 11 pressure zones. The District’s service area includes the communities of Lake St. Louis, Defiance, New Melle, Augusta, Dardenne Prairie, Dutzow and parts of O’Fallon, Weldon Springs, Foristell, Innsbrook, Wright City, and unincorporated St. Charles and Warren Counties.

Due to the significant growth of the Public Water Supply District No. 2 of St. Charles County the project evaluated the state of the existing water system and conducted a 15-year water system study to update water demand/growth rate projections and identified capital improvements to meet future demands.  The project included the following:

•   Updated the Water System Master Plan by evaluating the entire water system which included customer growth projections, evaluation of current and future water demand, evaluation of the existing water supply sources, and condition assessment of the existing water system facilities (including pump stations, storage tank exteriors, and well houses in the distribution system but not the water treatment plant or supply wells at the treatment plant).

•   Upgraded the existing GIS-based water system hydraulic model for the Dardenne Prairie, Foristell, Innsbrook, Lake St. Louis, New Melle, Weldon Spring, and Wright City areas of the District’s system.  In addition, analysis of flow delivery to the City of Wentzville was evaluated in the model.  The upgrades  included verifying and updating new and existing major system components of the water system, including the piping networks and tank, well, and pump station data.  A full model calibration was performed to validate the model.

•   Evaluated the water system performance by evaluating the hydraulic model under average day demand, maximum day demand, maximum day demand plus fire flow, and peak hour demand for both steady state and extended period simulations for the current year and every 5 years through the 15 year outlook.  Also, a water quality model analysis was performed to evaluate water age and THM’s.

•   Made recommendations to repair and improve the water system and deliver more water to the growing north and west portions of the District, especially the City of Wentzville.





O'Fallon , Missouri

Year Completed


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