O'Fallon Water Master Plan

O'Fallon Water Master Plan

Location: O'Fallon, Ill.

Client: City of O'Fallon, Ill.

Completion Date: July 2006

O’Fallon and Fairview Heights, Ill., are rapidly growing suburbs of St. Louis. The O’Fallon water system serves about 40,000 people and is projected to increase the service area population to about 60,000 people by year 2025. This projected growth will increase maximum day demand from 7.4 million gallons per day (MGD) to 12 MGD in 2025. All water is purchased from Illinois American Water Co. at a master meter. The system includes two ground storage and three elevated storage tanks, two booster pump stations and three emergency connections.

The city had an existing ESRI geographic information system (GIS) that contained base mapping such as roads, parcels and contours, but it did not include water distribution system data. A data collection effort was completed in which more than 900 sheets of as-built drawings were collected and digitized into the city’s existing GIS database. The as-built drawings provided the locations of all pipes, valves, hydrants, tanks and fittings as well as attribute data such as diameters and materials. The water distribution system would serve as the data source for the hydraulic modeling efforts and feed directly into the city’s existing Azteca CityWorks Maintenance Management System.

Once all the physical features of the water distribution system were defined in the GIS, the city’s customer billing data was attached to the parcel data layer through a geocoding process. The correctly located customers were then attached to the closest water system feature and provided a true existing demand distribution.

This GIS was integrated into an H2OMap hydraulic model. Major tasks included field testing, diurnal curve development, storage analysis, model calibration and verification, and modeling to develop water system improvements and associated capital improvement program to meet year 2010, 2015 and 2025 projected demands.

After completion of the model calibration and verification, the existing system is evaluated to determine the strengths and weaknesses of the system. Years 2010, 2015 and 2025 are modeled for maximum day, peak hour, minimum hour plus tank replenishment and maximum day plus fire flow.

Future improvements include two 1 MG elevated storage tanks, a 12-MGD booster pump station to replace the existing French Village booster pump station, a new supervisory control and data acquisition (SCADA) system, and additional transmission mains. These improvements will allow the city to continue to grow and improve pressures and available fire flow while meeting projected water demand.

  • Master plan
  • Hydraulic modeling
  • GIS interface
  • Field testings
  • Future water supply