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UNSATURATED ZONE MONITORING RESULTS THROUGH THE SECOND YEAR OF RECLAIMED WATER IRRIGATION AT THE HONOLULU BOARD OF WATER SUPPLY FIELD DEMONSTRATION PROJECT
Author: Steven A. Wilson, Ronald W. Crites
Date: 9/204
2004 WateReuse Conference

A field research project was initiated by the Honolulu Board of Water Supply to demonstrate the safety, efficacy, and value of reclaimed water for turf irrigation. To address potential concerns regarding protection of local ground water resources, a detailed unsaturated zone monitoring system was designed and implemented on field test plots. Twelve randomized field plots (16 feet by 16 feet) were laid out at a representative location in the area where reclaimed water would potentially be used for irrigation. Experimental design included irrigation with reclaimed water (R1 or Title 22 quality) at the agronomic rate and twice (2X) the agronomic rate compared with well water as a control. Bare soil plots and fertilized/non-fertilized variables were included. A programmable irrigation system was installed with micro-sprinklers in each corner of plots to provide even irrigation in all plot areas. Eight stainless steel suction lysimeters were installed at a 5-foot depth in each plot to ensure adequate sample volume and provide complete representation within plot areas. A weather station was provided to assist in schedul-ing irrigation and facilitate development of a water balance. Plots were established in December 2002 and sampling was initiated in February 2003. Soil percolate concentrations for nutrients, metals, and inorganic salts through the spring of 2004 are presented with a statistical analysis of differences between treatments. Findings represent effects from operation of a reclaimed water irrigation facility for the variety of conditions represented by experimental treatments.