Center Pivot Design for Effluent Irrigation of Agricultural Forage Crops

Balancing the continuous supply of domestic wastewater from effluent treatment plants with fluctuating crop water demands requires unique irrigation design strategies. A key design consideration when utilizing disinfected secondary treated city water is to maximize the re-use of effluent in winter months, when forage crop water demands are low, yet still produce minimal deep percolation. Twenty-seven center pivots in Palmdale, California required new customdesigned sprinkler packages to dispose of approximately 7,000 gallons per minute of treated wastewater. Through innovative design efforts, extensive testing and field experimentation, a standardized package has been adopted by the County Sanitation District of Los Angeles County that enables a highly efficient application of re-use city wastewater without groundwater degradation throughout the year. Many factors influenced the selection of the sprinkler package components including infiltration rates, application rates, soil moisture storage, distribution uniformity, pressure regulation, wind, and debris buildup.