Water Reuse Using Drip Irrigation and Micro-Sprinklers

A wastewater treatment plant with a design average dry weather flow of 0.9 million gallons per day was constructed in Laie, Hawaii. Existing environmental conditions and governmental regulations resulted in the selection of a unique reuse system as the primary disposal alternative. The disposal system utilizes 22.7 hectares (56 acres) of turf, agricultural, and ornamental plantings. Turf plots are irrigated with subsurface drip irrigation. The agricultural plots included banana and papaya plants that are irrigated by micro-sprinklers, while the ornamental plantings utilize both methods. A heavily instrumented 2.95 hectare (7.3 acre) demonstration project was operated for ten months before the full scale project was approved. A large subsurface disposal system is used for disposal when the reuse system can not be used. The system has been operated successfully for seven years.