That gives us much more background.
Is this, then, just a single-point exercise where the "leak" is staged, or do you still need to fly and film the length of the pipe?
Movie or stills? Presumably movie, as that is what most TI systems are. All Police/public service airborne units use gyro-stabilised fixed units on (almost invariably) helicopters. They are very expensive, but they do this for a reason - it is the only way that works reliably.
You might prove the concept with a hand-held unit at a known and pre-planned position but I doubt that approach would work for a survey along the length of the pipeline.
The plan should work as long as the tempretaure of the leaking water is different from the surface of the land it wells up onto - others will explain the sensitivity of commercial TI systems but they are pretty cute these days. If you are from a utility or water company why not approach your local Police ASU for some guidance on what TI can do, or failing that get the manufacturer of the imaging kit to stage a demo for you. If their reps smell a sale they'll move mountains to help...
Hate to take the glory away, but this is even more specialised than it seemed at first, but if you play it correctly you just might get to set up a flying unit with the specialise kit and do it yourself, but I think it will be a major project.
CANP. PINS. Hmmm. bugger all use IMHO. You need to state exact position at exact time days in advance - how can you do that with operational and weather delays? Worry briefly, then forget about it if you ever start a permanent outfit.
Good luck!