The final demolition of a former Sacramento police building has been halted again while concerns over an adjacent power station are worked out. Advantage Demolition was preparing to demonstrate Monday how the last two exterior walls could be pulled down safely next to transformers at a historic power station, now known as SMUD Station A, at Sixth and H streets. The station, whose origins date to 1895, supplies power to up to 40 percent of downtown Sacramento, said Sacramento Municipal Utility District spokesperson Dace Udris. Demolition of the building at Seventh and H streets began several months ago to make way for a 160-unit affordable housing project being built by the Sacramento Hou