491, 493, 495 Dean, Oct. 20 They've been doomed for a while. Now three houses on Dean Street just east of Sixth Avenue, and an industrial building on Pacific Street behind them, are getting closer to the wrecking ball. So forget 491, 493, and 495 Dean Street, the addresses of a smaller-scale, older-time Brooklyn. They will be obliterated for 664 Pacific Street, the address of the building known as B15, a 27-story tower filled with market-rate rental apartments, with a public school at the base. At the Community Update Meeting Oct. 14, Forest City Ratner executive Ashley Cotton said that an 8-foot-high plywood fence--not unlike the one across Sixth Avenue for the B3 site--should go up on Dean Street in front of the homes, where abatement (not demolition) work is ongoing. Then comes demolition by the contractor, Russo Demolition, after permits are issued. That means a fence (purple in the slide below and at bottom) just three feet from the curb (yellow). The first bui