Irrigation System Improvements

Laura Illanes
Staff, Facilities Services
laura.illanes@austin.utexas.edu

Introduction

The University of Texas at Austin’s facilities management initiated a comprehensive program in the fall of 2007 to develop and implement demand-side water conservation measures. These improvements are enabling the University to provide considerable annual savings of potable water on its main campus while demonstrating to the campus community a concerted step toward sustainability and responsible stewardship.

Background

The University’s demand-side water conservation program consists of several phases. The first phase comprised conservation of domestic water for the University’s main campus. This included retrofitting toilet and urinal flush valves with a low-flow type to reduce the amount of water used. It also included installing new or replacing existing faucet aerators with low-flow aerators to further reduce the amount of water used. The second phase consisted of conservation of process water for the main campus. This involved installing portable closed-loop chillers that reuse water instead of disposing water to the sanitary sewer after one use. This essay discusses the third phase of the program, conservation of water used for landscape irrigation systems on the main campus.

Method

An audit of the main campus irrigation systems was performed in the spring of 2008 by the general contractor, Water Management, Inc., with assistance from the City of Austin. The audit comprised an inventory of all irrigation control points with regard to water supply type, size, and location and an assessment of 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 irrigations systems and a review of the available funding led to the development of the following scope of work.

photo of spray-type sprinkler heads
BEFORE: Spray-type sprinkler heads create misting and drifting distribution, waste water, create puddles on the sidewalks, and blur visibility of university features.

photo of rotary-type sprinkler heads
AFTER: MP Rotary-type sprinkler heads provide a more focused and efficient distribution, conserve water, leave the sidewalks dry, and improve visibility of university features.

photo of evapotranspiration guage
Fig. 01: Evapotranspiration Gauge

Project Scope of Work

The project scope of work encompasses many components to address the deficiencies identified in the Method section of this document. Overall, the project is retrofitting the irrigation systems at 82 sites on the University’s Main Campus. The subcontractor, Sullivan’s Irrigation & Landscaping, under the supervision of Water Management, Inc. (WMI) as General Contractor, implemented the following measures:

Centralized Irrigation Management Program. A new computerized and centralized control irrigation management program was installed, programmed, and commissioned. The 82 existing automatic controllers were replaced with wireless controllers that can communicate directly with the new control program. Proper earth grounding was installed for all of the new controllers to protect them from lightning strikes and electrical surges. In addition, Landscape Services maintenance technicians were provided with five remote radios to allow them to inspect and maintain the irrigation systems more effectively.

The central computer is a Dell standard PC with a 42” LED, flat- screen monitor. It will be used to monitor, modify, and generate reports from the data the controllers gather from their respective irrigation zones. The proprietary software used to communicate with the controllers was provided by the manufacturer of the controllers and remote radios, Calsense. The controllers are Calsense Model ET2000e Enhanced Water Management Controllers. This device is the “brain” of each irrigation zone. Its purpose is to execute the programmed watering schedule or use a weather-based strategy, monitor water flow amounts, measure rainfall, and monitor for alarm conditions and react accordingly. The controllers allow staff to activate irrigation control valves from a remote location and receive the status on a handheld transmitter. Historical data is communicated back to the central computer and stored for analysis and report generation.

Improve Water Distribution Efficiency. High application rate spray sprinkler heads were replaced with Hunter’s matched precipitation (MP) low-rate rotator nozzles. This type of nozzle emits a larger stream of water and droplets, which is less likely to drift away as compared to a spray-type nozzle, according to Leadership in Energy and Environmental Design (LEED) specifications.1 The nozzles are also self-flushing upon start-up and shut-down to help eliminate clogging, and its arc watering pattern can be easily adjusted in the field without the use of a tool. In addition to the installation of the new nozzles, the subcontractors relocated, replaced, or repaired sunken, tilted, broken, or clogged heads. They adjusted the heads to avoid watering concrete, asphalt, fences, and buildings, reduce waste, and improve distribution uniformity. Improperly spaced sprinkler heads were relocated or removed to ensure even, head-to-head coverage.

Automatically Adjust for Weather Conditions. Two Calsense evapotranspiration (ET) gauges and three rain buckets were installed on the main campus. The ETs were installed in two different “climates” on the main campus, one ET near the Facilities Complex Building 3, and the other ET near Jesse H. Jones Hall. The ET gauges measure real-time daily evapotranspiration, which is used to automatically calculate station run times 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.

Measure Water Usage. Calsense digital flow sensors were installed at each controller to measure instantaneous and total flow. Instantaneous flow data is useful because it tells the controller that the system is delivering the designed flow rate. Total flow data can be used for trending analysis and budgetary planning.

Shut off Water Automatically. Master valves were installed along with the flow sensors. Together, they provide automatic shut-off capabilities to our landscaping staff. If a low or high flow rate (compared to a pre-programmed value) is detected, the controller will automatically shut off the current watering zone by closing the master valve.

The subcontractor’s representative, Markus Hogue, said that upon ordering components from Hunter and John Deere Landscape, he learned that the University’s project was the largest single (all at one time) U.S. installation of a water-conserving irrigation system.2

Project Cost

When the main campus project is completed by or near November 1, 2011, the University will have expended a total of approximately $2,103,000.3

Benefits to the University and the Environment

The University expects certain benefits for its main campus from the irrigation system retrofit project. These expectations are based on documentation provided by the general contractor, Water Management, Inc. (WMI), using standardized industry calculations. These include a reduction in water use, an increase in annual savings as a result of the reduced water use, and a considerable increase in the conservation of water. In addition to water conservation, the University’s reduction in water usage decreases the amount of water processed and pumped by the local water utility (City of Austin). This allows the University to play a contributing role in the local community by reducing demand on natural water supplies and avoiding harmful emissions of carbon dioxide equivalent (CO2e) into the environment as a result of the reduced production load on the city’s utility. Finally, an additional benefit expected is an increase in efficiency for the University’s Landscape Services maintenance staff.

Details of each benefit are discussed below:

Water Usage. The University expects a 28 percent reduction in irrigation water use as result of the improvements made to the irrigation systems.4

Bottom-line Savings. The University expects to yield savings of more than $500,000 per year (at 2012 rates), with a four-year simple payback, as a result of the reduced water use.5

Water Conservation. The University expects to conserve approximately 49 million gallons of water annually as a result of the reduction in water use.6

CO2e Emissions. The University expects to contribute to the avoidance of approximately 314,888 pounds of CO e emissions as a result of the reduction in demand from the local water utility, the City of Austin.7

Efficiency. Landscape Services expects an increase in maintenance efficiency with the centralized program, wireless controllers, radios, and irrigation distribution systems in place. According to Landscape Services Irrigation Supervisor Luis Garza, the efficiencies gained with the installation of the project are many. With the centralized computer, Garza has direct access to every controller from his desk so he can turn controllers on and off or change programs without going to each controller. He can 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. He can review water usage reports in different scenarios, such as scheduled irrigation or test and manual usage. The data from the evapotranspiration gauges automatically determines how much and how often to irrigate based on weather conditions. The handheld radios allow Garza and his staff of landscape maintenance technicians to turn stations on and off remotely. The device also displays flow rates, electrical output, and station information. As Garza explains, “the remote takes the place of one tech standing at the controller and turning on and off stations while one does inspections.”8

Conclusion

This demand-side water conservation program is providing the University with a robust, integrated irrigation management program, along with other modifications to existing automated and manual irrigation systems. These improvements provide management and system efficiencies and effectiveness for the University’s resources and represent a highly visible focus on sustainability over 125 acres of the main campus—the largest water-conserving irrigation system installed in the United States.

References

  1. Walla Walla Sprinkler Company. “Water Efficient Design Information: MP Rotator Overview Sheet.” Corporate Overview, Walla Walla Sprinkler Company, 2009.
  2. Markus Hogue, interview by Laura Illanes. Sullivan’s Irrigation & Landscaping, Business Development Manager (July 27, 2011).
  3. The University of Texas at Austin, Facilities Services; Patrick Mazur. Technical Staff Associate - Energy & Resource Conservation Specialist. Austin, August 2011.
  4. Water Management, Inc.; Dave Woods, Irrigation Operations. PowerPoint presentation, emails with spreadsheets, Alexandria, 2008.
  5. Ibid.
  6. Ibid.
  7. Ibid.
  8. Garza, Luis, interview by Laura Illanes. The University of Texas at Austin, Facilities Services, Landscape Services Irrigation Supervisor (August 4, 2011).