The Los Angeles Department of Water & Power?s converter station at the south end of the 850-mile DC Intertie, which carries 3,100 MW of imports, is undergoing a $100 million upgrade and will be down from October through December. The downtime coincides with the season of lowest power use, but a heat wave or outages elsewhere could create problems for moving power around. The California Independent System Operator has used the DC line when there were jams on the north-south AC lines, Paths 15 and 26. LADWP co-owns the station with Southern California Edison, which holds a 40 percent interest, and the Burbank, Glendale, and Pasadena public power agencies, which together have a 10 percent share. Tom Lanski, LADWP project manager, declined to comment on what would occur if there was a power surge or a bottleneck on the AC interties while the DC line was out. ?We don?t anticipate any problems,? said Steven Conroy, Edison spokesperson. ?The CAISO is ultimately responsible for managing the system,? he said, adding that if there was a power surge, the availability of other resources would be looked at as they are during times of high demand. ?It is something we are concerned about and another balancing act we will have to perform in October,? said Gregg Fishman, CAISO spokesperson. High temperatures can hit in October, which is also a time when power plants go off line for maintenance. He added that the DC line replacement work has been deferred for some time and ?needs to get done.? Temporarily losing the capacity of the intertie, which currently carries up to 2,000 MW because of modernization work, is not a big deal for Pasadena and Glendale. Glendale receives about 30 MW via the DC line, and about 250 MW of local generation is expected to be available if needed, said Larry Silva, the muni?s resource manager. There are also local supplies available to Burbank. It and Glendale would also be able to access electricity from Arizona, Nevada, and possibly Utah, with the choice of replacement power being based on cost. The converter station?s hefty mercury arc valves that have been in place since the 1960s will be replaced with state-of-the-art ones, which are far smaller and require a fraction of the upkeep, according to Lanski. The west-side converter station?s valves were recently upgraded. Ones at its sister station will also be replaced and moved to less seismic-sensitive ground. ?The station will be more robust and be able to survive an earthquake,? said Bruno Jeider, Burbank power resource manager.