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Setting out irrigation pipework
few years back I had a typical setout job.
A vegetable grower had been somewhere and seen a very large manicured lawn with a sprinkler system where all the sprinklers were lined up neatly in rows from several directions.
He decided he’d like that for his market garden.
This is the site
Enter me into the affray.
It was mid summer, temperatures hot, for me. Nights cool at 6-8å¡, daytime quickly around 25å¡ – celcius.
I was to establish a grid that served the best layout and gave the desired effect, with allowance for rows suited to their cropping machinery.
All easy stuff.
I established a base and gave them lengths between sprinklers.
It was about 100mmÌ÷ PVC pipe with a tee every 14 metres from memory.
I had a frantic call early one morning to say nothing lined up.
I knew I hadn’t made different measurements on successive rows and checked some pipe they had laying on the ground ready to put in the trench.
The lengths were 200-250mm different to what I had setout.
No one had accounted for the marked difference between daytime and evening/ early morning temperatures and the longer it lay on the ground the longer the pipe got.
Then there was a query as to my general setout and whether it would fit their machinery.
I suggested they ignore all fancy setout and drive their gear to check for fit.
I was somewhat amused when the gear arrived and the driver queried my measurements.
This is the measuring device he used to make the comparisons. There’s a GPS fitted to the tractor.
Following are some photos of progress along the wayIt was an interesting job that was somewhat overkilled with science.
I suggested they cut a template pipe the desired length, allowing for fittings and just use that.
It worked well and that was the end of my involvement.
I don’t think the desired outcome was entirely met, but the end result looked good.The project certainly had its challenges as the setout was given in the trench and the standups had to be vertical whilst they back-filled about 600mm, and keeping on line. No mean feat. Then there’s that sun effect.
Interestingly whilst I was doing my initial RTK pickup for design something hijacked my signal and things went haywire for a while. I gathered another radio was transmitting close by with same frequency.
All the setout was done with Total Station so that wasn’t an issue then.
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