PhD student Jim Berglund and I finally got to do a tracer test in the sinkhole near Tippery Spring in central PA. Ellen Herman from Bucknell joined us to monitor the injection water. We used our new fluoroscein loggers to capture the first arrival after about 24 hours. We can detect less than 1 ppb up to 400 ppb.
So far none of the neighbors have complained about turning the stream green so I think we stayed below the visible detection at the outlet end.