Monday, September 19, 2011

New WUEP research sites online! - Part 1 of 2

This summer’s work around the WUEP Irrigation Research Project has been somewhat different from that of previous years. The expansion of the study to include weather-based timers (or evapotranspiration (ET)-based) in addition to soil water sensors (SWS) resulted in a new approach to homeowner system retrofits (and new site initiation).

Because the ET timer factors irrigation zone details into system run time calculations (including sprinkler head type/application rate), this year zone redesign played a more critical role in the retrofit process. Poor zone design (such as head-type mixing, see image below) makes timer programming difficult can result in excessive water-use and inaccurate data. To eliminate this, new sites often required additional visits for zone redesign work before data collection could begin.

Rotor v. spray: there can be only one

Over the next several weeks, research sites initiated since July will be detailed and, since new site initiation has concluded, this summer’s efforts will be summarized.

Palmetto Bay

Out at the crack of dawn with the squirrels, we began this installation day at a homeowner property that has been a part of the irrigation study since last summer. Their soil water sensor system beset by all manner of malfunctions, the residents decided to continue with the study for an additional year only this time with an ET controller.

With the electric valves, backflow device, and water meters already in place from last summer, we were allowed to focus on installing the new timer and weather station.

We concluded the installation by removing all existing spray heads from the system. This permitted more accurate ET timer programming since all the remaining sprinkler heads (rotor or multi-stream spray) apply water at a more similar rate.

Our usual method for gathering data on a ET study site involves metering the system's mainline to tabulate total water use. Since this is a 2 zone system, both zones were metered last year for the SWS comparison study. Consequently, no additonal meter work was required.

Coral Gables

The day's next homeowner property featured a mechanical irrigation system on city water and required a complete retrofit.

We began with our favorite pastime: digging up and eliminating the indexing valve!

Due to wiring issues the mechanical timer was kept in place as housing for the power wire feeding the ET controller.

Other installation details included adding a backflow device to protect the potable water lines, electric valves for each of the two zones, a water meter on the mainline to collect water-use data, and mounting the on-site weather station that provides the ET controller with temperature and rain-depth information.

Much like the previous system, this one suffered from poor design: head-type mixing and excessive heads. Although we could not tackle the redesign work on this day, we made note of the changes required to improve the zones (eliminating heads and replacing all spray heads with multi-stream sprays) for subsequent visits.

Coral Gables, again

This day concluded with a homeowner property dying to work with us. A WUEP participant from the early days of the program, it was invited to participate in the research when its SWS burned out. So eager was the owner to take part in the research that she offered to have a power outlet installed so that the new ET timer could be accessible from outside the garage! It was an offer that could not be refused.

Beset by downpours and time constraints, our first day on the property was limited to installing the new ET-based timer.

Several weeks later we returned to advance on the work. We began by addressing the inefficient means of distribution and bid the indexing valve adieu.

We then installed a backflow device for potable line protection, electric valves for each of the two zones, a water meter on the mainline for data purposes, and mounted the on-site weather station.

A galvanizing lesson

Because this property dates back to the early days of the City Beautiful, all the underground water lines are galvanized steel. What we were not aware of during the retrofit is that these pipes also pack some serious pressure!

Fed by a turn-valve sub-meter, the pressure in the irrigation system was so excessive that a few days following our retrofit it fractured the new PVC pipe-work in three places around the water meter!

On our third visit to the property we replaced all the fractured fittings and tackled the redesign work. Since the large zones featured predominantley rotors, our objective was two completely rotor/multi-stream zones.

before redesign: spray heads

after redesign: multi-stream sprays

We set about removing some heads, replacing some sprays with multi-stream sprays and moving some rotors for better coverage. We also manually adjusted the water pressure at the sub-meter to avoid future fitting fractures.

See previous entires:


  1. Pretty good post. I just stumbled upon your blog and wanted to say that I have really enjoyed reading your blog posts. Any way I’ll be subscribing to your feed and I hope you post again soon.
    Delhi Water Fountain

  2. Interesting stuff! Love the pick of the ousted indexing valve! You guys should make shirts w indexing valves and a just say no logo!