Combining technology and water to conserve irrigation
Submitted on June 29, 2012 - 6:12am
University of Texas at Austin
Markus Hogue, Program Coordinator: Irrigation & Water Conservation, Facilities Services Landscape Services
Laurie Lentz, Communications Coordinator, Facilities Services/PMCS
John Burns, Manager, Facilities Services Landscape Services
The University of Texas at Austin’s facilities management initiated a comprehensive program in fall 2007 to develop and implement demand-side water conservation measures. During this project it was determined that the campus irrigation system lacked the qualities needed to meet the new sustainability requirements. As a result, the campus irrigation system was upgraded to use a central irrigation system to monitor water usage and flow, and the irrigation nozzles were replaced with more efficient ones.
The project started in spring 2011, and during that year the state of Texas experienced its worst drought in over 60 years. The irrigation upgrade came at a crucial time when the Austin community and city officials looked closely at the university to see how much water was being used by the campus and how the university was conserving. During discussions with the city and collaboration through workshops, the campus has created a working relationship with the city on irrigation water usage and a partnership in the city’s new pilot program of irrigation conservation.
An audit of the main campus irrigation systems was performed in 2008 by general contractor Water Management, Inc., with assistance from the City of Austin. The audit inventoried all irrigation control points with regard to water supply type, size, and location and assessed the current irrigation systems’ scheduling and water distribution efficiency. As a result of the audit, the following issues were identified and analyzed to develop appropriate solutions:
• Decentralized and various controller systems were unable to communicate with each other or to a central location.
• Irrigation distribution systems (sprinkler heads) were not efficient.
• Landscape Services staff could not automatically adjust watering schedules based on weather conditions.
• Landscape Services staff could not accurately measure water usage.
• Landscape Services staff could not shut off the water automatically when a leak occurred.
Analysis of the deficiencies in the existing irrigation systems and review of available funding led to the scope of work.
The university expects the following results from the irrigation system improvements:
• Water Usage. A 28 percent reduction in irrigation water use
• Bottom-line Savings. More than $500,000 per year (at 2012 rates), with a four-year simple payback
• Water Conservation. Approximately 49 million gallons of water conserved annually
• CO2e Emissions. Avoidance of approximately 2.45 metric tons of CO2e emissions as a result of reduced demand from the City of Austin water utility
• Efficiency. Increased maintenance efficiency with the centralized program, wireless controllers, radios, and irrigation distribution systems in place.
Specific efficiencies gained with the installation of the project include:
o direct access to every controller from a central computer.
o ability to monitor activity such as high and low flows and receive alerts when a break in the irrigation line triggers the water to shut off automatically.
o water usage reports that can be reviewed in different scenarios, such as scheduled irrigation or test and manual usage.
o data from the evapotranspiration (ET) gauges that automatically determines how much and how often to irrigate based on weather conditions.
o hand-held radios that allow the Irrigation Supervisor and his staff of landscape maintenance technicians to turn stations on and off remotely. Radios display flow rates, electrical output and station information, and allow a single individual to inspect a system.
The project consisted of four main aspects, implemented at the same time in order for the system to stay in operating capacity.
The first was to replace the older controllers with new, centralized controllers. This relatively simple change required disconnecting all the existing wires and removing the mounting bolts, then placing the new controller in the same location and reconnecting the mounting bolts and wires. Over 104 controllers were upgraded to the centralized system.
The second aspect was installing flow sensors and master valves. This was not easy to implement due to the location of the POC (Point-of-Connection) for the irrigation system. Wires had to be buried from the location of the flow sensor and master valve back to the irrigation controller. Many times this was underneath sidewalks, driveways, and even buildings. A few locations had multiple POCs, requiring many labor hours to complete installation. More than 108 flow sensors and master valves were installed.
Third, existing nozzles were replaced with distribution efficiency nozzles. This was also relatively simple; all that is required is to unscrew a nozzle and replace with a new one. Several zones were modified due to the coverage of the new nozzle. In one location over 400 nozzles were capped because they were no longer needed to properly irrigate the area. Over 18,000 nozzles were upgraded.
The fourth aspect was to install and set up the central irrigation system. A HUB and antenna were installed on the tower of the campus main building so that controllers in the field can communicate by LR (Low Radio) frequency. (LR was chosen in order to eliminate monthly charges that would be incurred by using cell phone or phone line connections at each controller.) With the central irrigation system operational, the HUB communicates back to a server that hosts the software; this connection is done by Ethernet. The controllers communicate with the server and gather information on water usage.
The system also uses ET (evapotranspiration) stations and rain buckets located around the campus. ETs were installed in two different “climates” on the main campus, one near the Facilities Complex Building 3, and the other near Jesse H. Jones Hall. The ET gauges measure real-time daily evapotranspiration, which is used to calculate station run times automatically so the irrigation system can apply the exact amount of water required, based on current weather conditions. The rain buckets tell the central control system how much rain has fallen; they also tell the system to shut down if it is currently raining.
2007 – Start of the comprehensive conservation program
2008 – Audit of the irrigation system and all components
2009-2010 – Phases 1 and 2 of the comprehensive program completed
April 2011 – Irrigation retrofit started
October 2011 – First meeting with the City of Austin on water restrictions
November 2011 – Retrofit completed
May 2012 – Irrigation pilot with the City of Austin began
In FY 2007-2008, a $16 million dollar bond package was sold to fund demand-side resource conservation projects, including water. The irrigation aspect of the water conservation project cost $2,077,313, which was paid for by bond monies and $243,400 from the university’s Replacement & Renewal Program.
The campus irrigation system was estimated to use 175 million gallons of water a year. Based on the flow data off the system, the campus used approximately 12 million gallons from January to the end of May. If this usage continues, the university anticipates saving 75-100 million gallons in the first year of the new system.
High flow alerts saved over 3.8 million gallons of water in the months of March, April, and May 2012, compared to the old irrigation system. With the old system a break would only be noticed during an irrigation inspection, or if an individual reported the problem. Such breaks are considered a water loss due to most of the water flowing onto sidewalks or streets.
The alerts also allowed Landscape Services staff to find valves that were either stuck on or very slow to turn off. The faulty valves would have gone unnoticed for months.
The new system can be controlled from anywhere in the world by laptop, iPhone or iPad. This allows shut down of the system if an unscheduled event occurs after hours, or troubleshooting a problem by phone without needing to send an individual to the site.
In May 2012, the university formed a partnership with the City of Austin, which is piloting an alternative irrigation compliance program that gives a monthly water use allowance (“budget”) based on square footage. Currently, the city limits the number of days irrigation is permitted. Although The University of Texas is a state entity and therefore not required to follow city water requirements, the university generally follows those requirements to demonstrate support of conservation and city conservation efforts. Since the new irrigation system gathers and reports flow data and square footage, the city can use that information to determine if their new requirements are attainable and whether the landscape can sustain the desired appearance. For all other locations of the pilot program the city must check water meters every month. The university provides the city with the ease and convenience of receiving a database with all the campus water usage and comparison to city water budget requirements.
Savings from the flow sensor and master valve combination was under-budgeted during the design process and found to be one of the most beneficial aspects of the project. This feature eliminated water loss due to a break and then alerted staff to the exact location of the problem, saving water and labor at the same time.
The new distribution efficiency nozzles require a longer run time to achieve the correct amount of applied water. Larger systems cannot always complete a run cycle in the allotted time. This has been addressed to some extent by the central system allowing multiple zones to operate at once, but only if the water supply can handle two or more zones operating together.
Under the new system, irrigation may operate more frequently than before. Public awareness is essential in order to show the campus is conserving water, even if the irrigation operates more days. A campus-wide email sent to all university faculty and staff explained the pilot program with the city. Since implementation of the new watering schedule, no complaints have been received about the amount of days the irrigation is being operated. Coverage of the new system in the campus newspaper, the Daily Texan, also helped explain the new system and pilot to the campus community. When the general public, as well as the campus community, sees campus irrigation in operation during non-typical watering cycles, and particularly during times of drought, a communication about the university’s irrigation practices is required.
Each centralized irrigation system allows for multiple programs, but most companies only use Program A. Landscape Services separated each irrigation distribution method, nozzles, rotors, bubblers, and drip into their own program, allowing universal changes without having to modify each system. Every controller is the same so that Program A is just for turf spray nozzles, Program B for rotors, and so forth. The next step is to modify each zone based on ET for shade and sun and then modify for crop coefficients based on plant material.
A methodology has been created to streamline and maximize the efficiencies with the new central system. The University is sharing this information with other campuses and municipalities around the United States to help them improve their own irrigation systems. UT’s motto is “What starts here changes the world”.