The subject of a recent call from a friend brought back memories of years teaching irrigation design at College of Marin and causing me to dust off buried literature used in the classroom. I realized what I taught still ran deep – Plan for success.
My friend’s concern was regarding the lawn in our town park. To be honest, I hadn’t paid attention to the park as road construction kept my focus elsewhere – specifically on the road! Nonetheless, the next trip to town found me stopping at the park and offered immediate insight for the concerned call. The town center lawn displayed partial to full concentric circles with three-foot dead grass pathways outlining the green lawn throughout the park. It could be described as an interesting mosaic or perhaps a dwarf mowed corn maze. At best, it had my attention and certainly piqued my interest as to what occurred to cause this scarred but thought-provoking pattern throughout! In fact, unconsciously, the tune “Follow the Yellow Brick Road” from the old childhood movie, The Wizard of Oz, came into my head! The sight grabbed me…I couldn’t walk away without a call to the parks department allowing my involvement.
Upon further investigation (will the water auditor ever disappear from this brain?) I noted the type of rotors used; their potential throw of spray given specific parameters such as the available pound-force per square inch (PSI) and gallons per minute (GMP) just to name a few. The capacity of these rotors are more than adequate to do the job, yet something was amiss.
One easily identifying issue was the lawn around each rotor was pushed down around the rotor from the force of projected water due to the sunken and slightly below grade rotor head. The spray was not clearing the height of the grass. That indicator made me wonder if perhaps a water pressure issue wasn’t allowing the rotor to fully open. I did locate a frost-free hose bib close by and found more than adequate pressure to push the rotors to their full height if the design of the irrigation system met the required criteria. Even so, while the lack of height of the rotor may reduce the throw of water it wouldn’t equate to the distance I found lost.
I measured the radius of the green circle and found the spray threw a mere 27 feet. The closest rotors were each 68 feet away. To achieve head to head coverage required for a well-watered lawn, these installed rotors could easily reach the needed 68 feet. I could not determine the number of heads found on each valve since I didn’t have access to the controller or valve location to find out that answer. Too many heads on one valve would greatly reduce the function of the system leaving the tell tale results found. A meeting of the minds will occur this week. At that time, we will assess the issues and uncover the mystery of the poorly designed irrigation system.
The point of writing this blog without an answer to this mystery is to give you pause for thought. Landscape contractors and those that jump through the hoops of learning about friction and pressure losses, elevations affecting water pressure, pipe types and sizes, or required gallons per minute available per valve will understand the concept of what it takes for planning out a good irrigation system before starting a job. There are multiple steps in the thought process to make an irrigation system work efficiently and effectively. An easy and simple example such as installing a shut off valve separating the water going into the house from the irrigation system will save a lot of headaches for without this step, it requires shutting off the entire water system to the house if the irrigation system needs work. These steps will be on the minds of trained professionals before purchasing materials The devil is in the planning details!
If a new irrigation system is on your bucket list of things to do, take the time to learn the avenue of getting good results or hire someone with the know-how to prevent a lot of heartache, otherwise you might be following the yellow brick road on your own property! OUCH!!!