I developed this irrigation repair technique out of desperation. A sprinkler head had launched itself out of the ground right beside me one day and landed in a potted plant. The resulting geyser was spectacular, but the location was horrible!
The area around this particular sprinkler head was surrounded in paving stone and brick, and worse, right up against a fence. To make things harder, I had installed a french-drain only a foot away! The riser's nipple was missing. Sure enough, a replacement stand-pipe wouldn't even begin to screw in! Obviously, the broken off part of the nipple was stuck in the t-connector - deep underground! Before I developed this technique, I would have had to dig lateral trenches about 2' long on each side of the connector, cut the supply lines off each end of the connector, added a sleeve and spacer, then glued in a replacement t-connector. Not this time! There was too much involved in digging this connector out of the ground!
I have a special purpose tool I'd bought from The Home Depot just for this problem. It's the PVC variant of an "easy-out." Unfortunately, it wouldn't work! I couldn't get enough pressure (the connector was buried just about the extractor's full length), and I kept scraping my knuckles against a fence post. The stand-pipe wasn't PVC, it was vinyl. It was so slick, the knife edges of the extractor wouldn't bite into the inside edge.
But vinyl melts! I have a 1200 watt heat gun I'd bought for paint stripping. The extractor's tip is metal and by using this heat gun, I got the extractor's tip hot. Real hot. Sizzling hot! By pushing the extractor straight down the hole, it gently melted into the broken off nipple - deep underground! I let it set and cool for a few minuets before giving it a twist. Two seconds later, the broken off nipple was extracted!
After screwing in a replacement riser, I cycled the irrigation pump to that zone to rinse out all of the dirt that had fallen into the connector. I put a new sprinkler head on the replacement riser, and guess what? That irrigation repair was done. Not only done, I didn't have to dig one spade of dirt!
A few weeks later, I had a different problem. I had mounted new window boxes along one side wall of my home and wanted to use my in-ground irrigation system to water the new flowers. I had a capped off riser right where I need to place a 4' riser. Unfortunately, this was an old steel riser that I'd bumped into several times with the mower, and when I removed the pipe it left the t-connector's threads stripped and choked with rust-scale! Unlike most of my irrigation repair projects, this line is very shallow. Shallow enough for me to scrape away the top to really see the damage.
There wasn't anything I could do to thread the new riser into place, I was going to have to replace the t-connector - or maybe not. I have a pretty complete shop and I have metal working tools to tap holes for screw threads, or cut outside threads for bolts. Since I had to go to The Home Depot or Lowe's anyway for a replacement t-connector, why not see if they had a tool for pipe threads?
The staff at Lowe's laughed when I asked them for a tool to cut internal 1/2" pipe thread for an underground PVC t-connector! Their only advice was to dig it up and replace it. No Way! The staff at The Home Depot didn't laugh out loud, but they also suggested replacement fittings.
I did buy the fittings, but I also found the perfect tool - an 18" length of 1/2" steel pipe! Once again, the 1200 watt heat gun came to the rescue. By heating the pipe end, the thread section, I was able to plunge it into the buried t-connector. It sizzled as it sank in and I quickly worked it in deeper as I screwed it into place. Without letting it sit, I unscrewed the steel pipe to prevent it from welding into place. I repeated this operation several times until all of the pipe's threaded section was within the t-connector's nipple.
Guess what? The new replacement 4' PVC riser threaded itself right in! By using heat, pressure, and steel threads, I was able to partially melt the underground t-connector and cut new threads. Not a spade full of dirt was dug up for this irrigation repair!
Not all irrigation repairs can use this technique. Let's face it, if the t-connector's nipple or connecting pipes crack or break, you will have to dig. But try this tip first and see if it works. You'll know within minuets if there's a more serious problem. You'll get wet standing there, but you'll quickly see upwelling around the sprinkler head in operation if there's a broken pipe or cracked nipple. Oh well, at least you gave it a try!