In what he said was his first act of civil disobedience, Dedham selectmen chairman Mike Butler was charged with trespassing earlier this month for refusing to leave the area on Elm Street where Algonquin Gas Transmission LLC is building a natural gas pipeline. Butler said he had no regrets and was acting alone, although the Board of Selectmen has publicly opposed the pipeline running from Westwood through Dedham to West Roxbury. In April, the board asked the Federal Energy Regulatory Commission to reconsider its March approval of the project. When the federal agency allowed construction to start in June before holding a new hearing, the town filed suit in US District Court to stop the work. "I felt it was important to call attention to this," Butler said last week, adding that he is concerned about the safety of the project. "It's 3 miles of pipeline that will be crossing heavily populated and highly developed streets in Dedham," he said. Butler, who has been a selectman since 2007, pleaded not guilty to the trespassing charge on June 18 and is scheduled to return to Dedham District Court in mid-July.