I was near the Los Angeles International Airport (LAX) for a few days this past week, and was hearing someone using 167.2500 MHz, 100.0 PL for some sort of general communications. The traffic appeared to be simplex, construction related and occurred over several days. Finally on Sunday, while waiting at LAX for a flight, I heard traffic that indicated they were painting the edge lines on new taxiways at LAX.
I have no idea who this might be and why they are using this frequency. This frequency is part of the federal interoperability pool of channels set aside for federal/local communications. This particular frequency is known as "LE-2", if a repeater, or "LE-6" if simplex.
This frequency is part of the federal interoperability channel plan found in the DHS National Interoperability Field Operations Guide (NIFOG), which can be found here: http://www.dhs.gov/national-interoperability-field-operations-guide