Site Overview and Hydraulic Layout
Auburn University's irrigation system in Auburn, Alabama, manages both grass turf with traditional irrigation and artificial turf with large rotors. The site utilizes four wells (Wells 1, 2, 3, and 5—Well 4 was removed from service due to poor production) along with a city water meter as makeup water. All water sources feed into a single cistern, which then supplies a pump station. The pump station delivers water to the main lines serving the various irrigation zones.
The system includes two different main line sizes: a 4-inch main line for landscape zones and a 12-inch main line for the big rotor zones serving the artificial turf. The central challenge is managing a relatively small cistern that can be drained in less than an hour when the pump station runs at full capacity, while the cistern recharge takes considerably longer. This requires careful management of both water flow and the multiple water supply sources.
Hardware Components
The system uses a single BaseStation 3200 controller with one substation to extend wire reach for zones located beyond standard wire specifications. The hardware setup includes:
- Flow sensors for monitoring water usage
- Master valves for system control
- A hydrometer combining flow measurement capabilities
- An event biCoder (event switch) to receive input from the pump station
Despite the system's complexity, it operates with fewer than 200 zones, which could technically be managed by a single BaseStation 3200.
Understanding the Two-System Approach
The programming strategy divides the system into two concurrent operations. The first system manages water sources upstream of the cistern—the wells and city water supply feeding into the cistern based on water level. The second system manages irrigation downstream of the pump station—all zone programming and scheduling for actual irrigation delivery.
These two systems run simultaneously. While irrigation zones are watering, the wells are independently monitoring cistern levels and turning on or off as needed to maintain adequate water supply. This concurrent operation eliminates the need for complex calculations to predict run times and flows, reducing human error and maximizing system efficiency.
Program Structure for Water Source Management
The controller utilizes multiple programs from its available 99 programs to manage the water sources. Programs 96, 97, 98, and 99 are dedicated to Wells 1, 2, 3, and 5 respectively, while Program 90 manages city water. Each well operates as the only "zone" within its dedicated program, with programs starting and stopping based on cistern level conditions rather than time-based schedules.
This multi-program approach is essential because the water source management requires separate programs from irrigation scheduling. Without the capacity for numerous programs, this type of sophisticated water source management would not be possible.
Configuring Event-Based Program Start Conditions
1. Navigate to the program settings for the well program (for example, Program 97 for Well 2).
2. Enable all days of the week to allow the program to run any day when conditions are met, rather than restricting it to specific days.
3. Remove the start time from the program. Without a start time, the program will not use time as a start condition.
4. Configure the event switch (in this case, RP00920 at the pump station) as the start condition. The event switch receives input from the pump station based on cistern level readings from a level transducer, translating external conditions into the BaseStation system via the two-wire path.
The event switch triggers when the cistern reaches a low enough level that requires refilling. Because the pump station has programmable intelligence with multiple set points, a single event biCoder can handle both start and stop functions. The pump station monitors the level transducer and changes the switch condition at specific water levels, providing precise control without requiring a simple float switch that would only provide a few inches of range.
Setting Program Stop Conditions
1. Configure the same event switch used for starting to also serve as the stop condition.
2. Set the condition so that when the event switch opens (indicating the tank has reached a sufficient level), the program stops.
This dual-purpose use of a single event switch is possible because the pump station's sophisticated programming provides different set points for starting and stopping, rather than relying on a basic float switch that would create only a narrow operating range.
Configuring Run Time Parameters
1. Set a run time of 60 minutes for each well program. This provides sufficient time to fill the cistern under normal conditions.
2. Understand that the event switch will interrupt and stop the program before the 60-minute limit if the cistern fills to the target level.
The run time serves as a maximum duration rather than a fixed watering period. With four wells potentially running simultaneously to fill the cistern, having an adequate run time ensures the system can achieve its goal while the event switch provides the actual control based on cistern level.
Disabling Global Conditions for Water Source Programs
1. Locate the Obey Global Conditions setting in the program configuration.
2. Uncheck this option to opt the program out of global conditions such as rain sensor input.
This setting is critical because water source programs must continue operating even during rain events or when global shutdown commands are issued. While irrigation zones should stop during rain, the cistern filling operation is part of water movement within the system, not water application to the landscape. The wells need to maintain cistern levels regardless of weather conditions or system-wide irrigation shutdowns.
Unchecking this option also prevents the program from responding to global commands like "shut down all controllers," which users might issue across their entire account. Even when all irrigation is intentionally stopped, the water source management must continue functioning.
Training Users on Proper Shutdown Procedures
Educate system operators to use rain shutdown features rather than turning the controller dial to the off position when they want to stop irrigation. If the controller is turned completely off, the water source management programs also stop, preventing the system from maintaining proper cistern levels.
Using the rain shutdown function stops irrigation zones while allowing the water source programs to continue operating. This ensures the cistern remains full and ready when irrigation resumes, particularly important after rain events when the cistern should be topped off in preparation for the next irrigation cycle.
Excluding Water Source Programs from Concurrency Management
1. Locate the Include with Total Control or Concurrency setting in the program configuration.
2. Disable this option for all water source programs.
This setting manages hydraulic capacity by controlling how many zones can operate simultaneously on the main lines. Water source programs do not draw from the irrigation main lines—they contribute water to the supply side of the system. Including these programs in concurrency calculations would incorrectly limit the number of irrigation zones that could run simultaneously.
Similar to how lighting programs are excluded from hydraulic calculations because they don't use irrigation water, well programs should be excluded because they add water to the system rather than consuming it from the main lines.
Understanding Schedule Priority for Water Sources
Schedule priority settings do not apply to the current configuration at Auburn University because all water sources (wells and city water) are contributing to the same cistern. However, if the city water supply were configured as a backup or secondary source rather than running concurrently with the wells, schedule priority could be used to establish which source takes precedence.
In a backup configuration, you could set the wells to a higher priority and city water to a lower priority, ensuring the wells run first and city water only activates when needed as an emergency or supplemental source.
Setting Up Multiple Main Lines
1. Navigate to the Flow Setup tab in the controller interface.
2. Select Main Lines to access main line configuration.
3. Create separate main line configurations for each distinct pipe size in your system. Auburn University has two main lines: a 4-inch main line for landscape zones and a 12-inch main line for the large rotors serving artificial turf.
4. Map out which zones connect to which main line. This requires understanding your system's physical layout and pipe infrastructure.
Proper main line assignment is essential for the controller to manage flow and concurrency correctly. Zones must be assigned to the correct main line based on their actual physical connection in the field.
Configuring Main Line Flow Parameters
1. For the 4-inch main line, set the Design Flow to 200 gallons per minute (GPM), which represents the maximum capacity for that pipe size.
2. For the 12-inch main line, set a much higher design flow limit to reflect its greater capacity for the high-demand, high-flow, high-pressure zones serving artificial turf.
3. Configure any advanced flow variants specific to each main line if needed for your system.
4. Set main line zone delays if required for your hydraulic conditions.
Assigning Zones to Main Lines
1. Within the main line configuration, open Zone Assignment.
2. Assign each zone to the appropriate main line based on its physical connection in the irrigation system.
3. Verify that all zones are assigned to a main line. Zones that are not assigned to any main line will run independently without concurrency management, as the controller has no information about their water source or hydraulic relationship to other zones.
Zone assignments are rarely sequential or organized in a neat pattern, especially on campus sites that have been expanded over time with multiple construction phases. Don't expect zones 102 through 124 to all be on the same main line—the physical layout determines assignment, not the zone numbering.
Understanding Manage by Flow
The Manage by Flow feature allows the controller to automatically combine multiple zones on a main line to maximize hydraulic capacity. For example, on a main line with 1,200 GPM capacity, the controller can puzzle-piece together two 600 GPM zones or any combination of zones that totals up to 1,200 GPM. This maximizes water window efficiency by running multiple zones simultaneously rather than sequentially.
At Auburn University, Manage by Flow was initially disabled due to a 15 GPM leak in the system. The leak created inconsistent flow readings—showing different amounts depending on whether the pumps were running or at rest—which prevented accurate flow learning. The controller detected and reported the leak, but it took several months to locate because it was underneath a sidewalk near a building on the 12-inch main line.
After the leak was repaired, the system could be configured to learn individual zone flows accurately, enabling the Manage by Flow feature for future operation.
Learning Zone Flows Accurately
For Manage by Flow to work correctly, the controller must learn the actual flow rate of each zone. If a zone actually flows at 115 GPM but the system learns it as 100 GPM due to a leak or other issue, the Manage by Flow calculations will be incorrect. This leads to constant fault messages, errors, and unreliable operation.
With a variable leak like the one at Auburn University—where the leak amount changed depending on system pressure and pump operation—the learned flows were unreliable across different flow ranges. A leak might represent one percentage of total flow at 1,200-1,300 GPM output but a different percentage at lower flow rates, making it impossible to get consistent, accurate zone flow data.
Flow learning should only be performed after confirming the system has no leaks and all components are operating correctly. Once the system is leak-free, learned flows will be accurate and Manage by Flow can optimize zone scheduling effectively.
System Integration Summary
The complete Auburn University system integrates multiple sophisticated functions:
The upstream water source management uses dedicated programs (90, 96, 97, 98, 99) to control wells and city water based on cistern level monitoring through an event switch connected to the pump station. These programs operate independently of time schedules, responding only to water level conditions. They are excluded from global conditions, concurrency management, and rain sensor input because they manage water supply rather than water application.
The downstream irrigation management uses the remaining programs to schedule and run irrigation zones on two separate main lines with different capacities. The 4-inch main line serves landscape zones with a 200 GPM design flow, while the 12-inch main line serves high-demand artificial turf zones with greater capacity. The controller manages flow on these main lines to keep the pump station operating at its optimal performance point while compressing the watering window and preventing both cistern overflow and depletion.
This configuration demonstrates how BaseStation technology manages complex secondary water sources efficiently without requiring extensive manual calculations or creating opportunities for human error. The system automatically balances water supply and demand across multiple sources and delivery systems, maintaining optimal operation without constant operator intervention.
Video Walkthrough
Video originally published January 2021.
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