The primary project objective was to validate the retrofit of an existing landscape irrigation system with a smart water conservation system to reduce potable water use by as much as 70% in support of meeting EO 13693. Additional performance objectives were to validate energy reduction, cost effectiveness, and system reliability while maintaining satisfactory plant health.
The demonstration was conducted for two different climatic regions in the southwestern part of the United States, where a typical DoD building landscape irrigation system was retrofitted with an integrated suite of commercially available water conservation technologies designed to decrease potable water usage. The demonstration sites were Naval Base Ventura County (NBVC) Port Hueneme, California and Fort Hood, Killeen, Texas.
The smart water conservation system demonstrated during this project was composed of an integrated suite of commercially available technologies for irrigating landscape (i.e., turf and low-water demand ground cover). The primary system components include the following elements:
The smart water conservation system at NBVC met primary water reduction goals and all of the additional performance objectives with the exception of economic payback. The system did not meet the economic payback period due to the high cost of the water harvest tank, relatively low cost of potable water, and relatively small size of the smart turf plot. However, as the amount of irrigated landscape is increased, and/ or the cost of water increases, the payback period will trend to a more favorable figure due to the substantial water reduction provided by the ET controller.
A number of specific troubleshooting issues were encountered during the demonstration, including reliability of controller equipment and diversion of first flush runoff to prevent system fouling with particulates. Where water storage is required for system effectiveness, capital requirements for tank storage limits the cost-effectiveness of the systems. Offsetting potable water with rain water to irrigate turf landscape at the NBVC site, where there is minimal to no summer rain, would require a larger tank (over 20,000 gallons) to store winter rain. In southern California, the goal is to install the largest tank possible to meet summer irrigation requirements. However, the economics do not indicate that there is a reasonable return on investment.
The ideal geographic areas to implement a smart water conservation system are locations such as Tucson, Arizona and Fort Hood, Texas which receive summer monsoonal rains that replenish the water harvest tank during the summer months when demand is greatest. In addition, facilities in these locations are also known to generate large amounts of air conditioning condensate. Areas that have high local water costs or limited water supply options may also benefit from water harvest.