Help, We have been called in to repair a leak in a geothermal closed loop system at a local school. System is approx 15 years old. System was hit by utility contractor installing new electric service approx. 10 years ago. Two contractors were called for pricing to repair, nether was hired repairs made by GC plumbing contractor who went bankrupt. Logical place to look for leek would be where electric service crosses loop field we thought. We hired local franchise of national leak detecting firm. Owner has 16 years leak experience and after two days I feel he is competent but was noble to locate leak. Day one air and water was introduced into leaking loop lateral and he used various microphones to search for leak. No luck. Day two 360 cubic feet of helium was forced thru lateral and helium detector could not locate. Any ideas appreciated. Doug

how big is the leak? How many gallons per day?

Hey Doug,
Here is my favorite:
Are we sure the leak is outside in the field? Has the inside work and transmission lines been as thouroughly tested and inspected?
Eric

2" poly lines come into pump room and have been valved off isolating leek. No visible signs of water leak and no helium detected.

Leak is approx. 600 gallons per day. No visible wet spots after 60,000 + gallons

Strange thing is supply side of this loop will pressure test and hold 100 psi. Return side where presumably the leak is will hold 10 psi. This makes s suspect that leak is possibly 25-30 feet deep given estimated static water level of 6 feet

just throwing out ideas. If you know where the header tranch is, you can crimp each loop until PSI increases. Then at least it is isolated to a loop. System might function without that loop until fixed.

We have used tube pincher to isolate kinked loop before, it is a good strategy.
j

This is a pure guess, but positioning some type of air/water vapor detector inside the tubing and then pulling a vacuum on it might work. Concentration will be highest right at the leak.

System is functioning having gone thru one winter and one summer with this series of loops valved off. Lowest return temp this winter was 38 degrees farenheit. This loop represents 20 percent of the field. Still curious about the 10 psi pressure in the leaky side of loop. Does my physics make sense? I equate this to a waterline gauge we use in turbine pumps. 10 psi represents 23.1 feet of head pressure. Is it possible to have a leak 20+ feet below ground on a vertical portion of pipe??

how do you separate the supply side from the return side?

I don't think the 10 psi means the leak is down 23 feet as you would have water in the loop as well as surrounding the loop. They should cancel each other out.