- McPherson Water Master Plan
The McPherson BPU water system serves more than 17,000 people, has a high industrial demand and is experiencing steady growth. This growth will increase the service area population to about 20,000 people by year 2026. This projected growth will increase maximum day demand from current 10 million gallons per day (MGD) to 12 MGD in 2026.
The system consists of 12 wells, two elevated storage tanks and a volatile organic compound (VOC) water treatment plant. The VOC treatment plant treats TCE contaminated water from three wells with an air stripper, polyphosphate to sequester hardness, chlorine for disinfection, and includes a clearwell and three high service pumps. The wells are in an intense groundwater use area, which limits available groundwater. Two of the wells have nitrates with concentrations near or above the drinking water limit of 10 mg/L.
A geographic information system (GIS) was developed from existing AutoCAD drawing files. The existing CADD line and text data were imported into an ArcGIS geodatabase model that was developed to support the water master planning effort. The geodatabase served as the data repository for all master planning and modeling activities. The geodatabase model was populated with both drawing and attribute data including hydraulic model properties such as diameter, material and lengths of pipe. In addition to the data extracted from the CADD files other pertinent information was developed to support the model such as elevations for fittings and facilities and roughness coefficients.
The GIS was not only used to collect information about the physical distribution system; it was also integral during the demand distribution phase. A process called geocoding, in which customer billing data was placed throughout the city based on meter address, was used to place actual metered water usage across the entire city. Once the meters were placed, the GIS was used to attach water demands onto the appropriate water pipe in the system, resulting in a highly accurate and efficient existing demand distribution for the hydraulic model. Existing and future land use analysis was performed to locate growth areas for proper sizing of improvements. The distribution system, customer data and planning data from the geodatabase was used to build the WaterCAD hydraulic model.
Major tasks include 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 2011, 2016 and 2026 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 2011, 2016 and 2026 are modeled for maximum day, peak hour, minimum hour plus tank replenishment, and maximum day plus fire flow.
This project includes two potable water system models and a raw water model. The first potable water model evaluates the system with the wells spread across the existing system; the current configuration. The second potable water model evaluates the system with the wells pumping to a central water plant for treatment and distribution. The raw water model evaluates the ability of the wells to provide water to the central plant.
Two water plant options are evaluated. The first looks at nitrate treatment of the three wells that pump to the VOC plant to levels of 8, 5 and 2 mg/L. The second plant option evaluates a central reverse osmosis water plant.
Future improvements include a new elevated storage tank and additional transmission mains. Additional work is ongoing to increase the systems water rights.
- Master plan
- Hydraulic modeling
- GIS interface
- Field testing
- Future water supply
- Water treatment