It still makes me wonder about whether flyover surveys are being done or increasinly needed to find buried sources. I remember reading the obituary of a retired Pennsylvania Bureau of Radiation Protection employee who came across a Rem/hr source in a sidewalk in his travels and lost the location before he could get back to it.
The Staten Island Great Kills Park is a great example: "In August 2005, the New York Police Department, with the Department of Energy, conducted an anti-terrorism radiation flyover survey. The survey was intended to provide a baseline of radiological activity, in order to catch a suspicious construction of a dirty bomb.
They didn’t find a dirty bomb—but there was plenty of radiological activity. Surveyors found 80 radioactive locations in the city, one of them being Great Kills Park in Staten Island, one of the city’s five boroughs. The Park is a popular place near a suburban enclave inhabited by cops, firefighters and other unsuspecting residents. The Park, more than 500 acres of woods surrounding softball and soccer fields and a marina, was constructed from garbage dumped in the bay between 1944 and 1946. Unregulated and illegal dumping has a long history in New York City."
