This isn't very surprising to me as the NRC allows alternate methods of warning other than outdoor sirens. Let's do some quick math.
109 sirens in the VC Summer EPZ
109 x 4 batteries at each siren site
= 436 batteries
If you figure about $100 a battery, that's $43,600 every 3 years or so to replace the batteries, plus probably another $50,000 in labor costs to change them out. Add yearly maintenance to the system and then parts and you're likely looking at well over $200,000 every 3 years to maintain the system. From a business standpoint, I'm sure the IPAWS system is substantially cheaper than this since the framework is already there, and would arguably be more effective than the siren warning system by itself. However, I believe in a multi faceted warning system, so from that standpoint this isn't the greatest of ideas. I'm sure that the sirens will likely be offered to the local municipalities and counties surrounding the plant, however, so this likely isn't the end of the entire system, granted the agencies that they are offered to decide to maintain them.