MARBLEHEAD – The Planning Board has postponed a decision on a 20-unit condominium development on Green Street until July.Board members met briefly Tuesday night with Attorney Paul Lynch to discuss the status of an application by Lynch?s client, Redstone Building Corp.Town Planner Becky Curran told Lynch the board made a May 7 site visit as scheduled and has received some of the material it requested in April, but is still waiting to see new traffic and drainage reports.Since the June meeting of the board would fall on the day of the town?s special election, the board members continued the application until July 12.That decision disappointed two abutters, Steve Chaisson and Richard Forbes, who said they learned about the board meeting at the last minute.Curran took Chaisson?s name – he is the only residential abutter – and said he would be notified of future meetings.?They (Redstone) will submit the reports we requested in advance of the next meeting and we will hire an expert to review them and people will be able to speak at the next meeting,” Curran said.Chaisson, who bought his home in 1987, appeared unaware that Redstone had purchased several single-family lots next door and combined them into a 3.67-acre site.Both men expressed curiosity about the process Redstone is following.Redstone plans to use a 1990s incentive zoning bylaw to build 20 two-bedroom condominium units at Green Street and West Shore Drive, in 10 townhouse structures, seven on the street and three at the back of the lot. Two units will be affordable housing. This is the first use of the law since it was passed.