Hope Mrs. M2 is coming to grips with the accident. Glad Penny was not aware or got the visual.
So, there was repairs required on one of the above ground, elevated flumes on the main ditch that feeds all of the system, including my service ditch. Every time the ditch shuts down, or there is a failure at the creek it takes quite a while to restore water and pressure, 3-4 days for the lines to fill our system.. Have been struggling to get the line to full the last few times and heading up to the ditch found a strange condition with the vent riser that evacuates the air from the pipe as it fills. Usually when you remove the vent pipe riser water bubbles out, well recently there was a huge blast of air prior to the water daylighting. It was apparent there was some sort of vapor lock occurring.
Had the water company up there and they always say, "air in the system on your side" and again they did not see a problem. One note, they replaced a bad 3/4" valve, a miner's type valve that had failed with a 2" gate valve. Was noodling this all last night and in visiting the ditch today it dawned on me. see photo
The gate valve is on the ditch side of our system as shown in the photo. With the increased valve size the water volume was overwhelming the vent (vertical 3/4" pipe) tee where post vent it is bushed down to the 3/4" union. This was creating too much water pressure and not letting air out of the pipe to the vent. no vent, no fill...
So, while up there today I shut the gate valve down to a point where the flow would not fill the 2" venting tee before the bush down and reestablishing the vent operation. Took me about 3 struggling line fills to figure this out, and the water company guys could not, and did not either after multiple trips up there. This reduced flow is likely about what the old valve provided. Once the line refills the vent will no longer push air out, but suck air in so I will open the gate back up completely.
This gravity line is a giant mystery where it shouldn't be really. But after 6 years and taking over the repair and maintenance a couple years back I learn something new each & every time...
I may just be considered a plumber someday.... Or maybe even a hydrologist??