According to the airport diagram, there is a “Fire Station” located at Z-Z2 on the south side of 08-26. The Tower called CFR-74 (Crash Fire Rescue unit 74?) about 30 seconds after the crash, receiving a garbled response (CFR-74’s read back?) nine seconds later. The tower then clears CFR-74 to: " … proceed as requested." It seems that the ARFF unit was already manned and ready to go, plus, it seemed that Lewiston Tower expected them to be so. It appears that they may have some enhanced form of ARFF capability above and beyond the requirements of 139.319 that you cited … or maybe an unscheduled charter was due. I’m rambling here, but I guess the gist of my comment is that I agree with your interpretation of the standard and that the response time wasn’t all that bad.
The three minute response time that you cited includes arrival and beginning application of extinguishing agent. They missed that mark by about 40 seconds. What really puzzles me about the ARFF response is the apparent timid approach to the burning wreckage. The ARFF vehicle appeared to stand off quite a ways and shoot foam from that position. This indicates to me a lack of familiarity with ARFF techniques. In the ARFF drills I’ve witnessed, extinguishing agent application began as the unit neared the target and continued as the unit approached the target as closely as possible. I guess that according to the book, the ARFF response was O.K.; however, in my opinion, it could have been better.