MARBLEHEAD – The Planning Board has once again postponed a decision on a 20-unit condominium development on Green Street – and there is a possibility the final decision won?t be made until fall.Board members Edward O. Nilsson, Karl Johnson and James Bishop met briefly Tuesday night to consider other applications. Town Planner Becky Curran said the continued hearing has been postponed until Aug. 9.?We?re still waiting for information,” she said. “We received the drainage report but we?re waiting for a report on traffic.”Attorney Paul Lynch, the lawyer for Redstone Building Corp., was asked to supply the board with new reports on drainage and traffic in May. Once the board has the reports the board will hire a consultant to review them, paid for by Redstone.Redstone is also likely to face questions from abutters who have attended previous segments of the hearing.Asked if final approval could be delayed until fall, Curran agreed.Redstone has purchased several single-family lots at Green Street and West Shore Drive and combined them into a 3.67-acre site. Using a 1990s incentive zoning bylaw, Redstone plans to build 10 townhouses on the property, seven on the street and three in back. Each structure will contain two condominiums and two units out of the 20 will be affordable housing.