hereCadent says the issue isn't to do with gas leaking out, but water getting in, as even a tiny amount can cause them to become blocked.The pipes can run for long distances underneath footpaths and verges, gardens and driveways so it can be hugely disruptive if engineers need to dig it all up to otherwise find the source.Cadent heard about former police dog sergeant instructor Steve Foster and his specially-trained English Springer Spaniels, and brought them to the North West for the first time