So you do understand that the pressure in a domestic supply main...

So you do understand that the pressure in a domestic supply main out in the street is about 50 psi, right? And when some doofus puts a backhoe through one the fire brigade turns up pretty damn quick to water spray it and the local area is evacuated because of the fire risk until the line can be isolated.
And we all know that the pressure in this well is around 6750 psi, correct? So what are the chances that it won't flare, when released under controlled conditions.
It is logical to assume that given the hot weather, that you'd run your test in what is usually the coolest part of the night, i.e.in the early morning.
( The pressure in your house lines is regulated by that inline steel box with the slow spinning numbers, i.e. the regulator and is only 1/3 psi.)