In order to go a step beyond the basic checks, I installed a new logger that we are trying by Telog which can monitor for transients and capture impulse data. I attached the logger to a hydrant at the end of their street and got the reading attached to this post. There have been a few instances of this occurrence and one matched up (time wise) to the complaint of pipe noise. This appears to be a local issue, meaning the source is not due to our operations or hydrant testing, etc.
Talking to others internally, there was at least one case where a customers faulty ice maker was causing similar issues for adjacent customers. I found it hard to believe that plumbing issues with one house could be transferred to neighbors, but this might be one of those cases. Does anyone have a similar experience who can offer advice which I can pass on to the customer on how to resolve?
Thanks in advance!