by Dave Copeland Developers of commercial and residential real estate are being blocked in their effort to bring new construction to market, thanks to a pair of state-ordered moratoriums on non-essential work against two of the biggest gas utilities of Massachusetts. Columbia Gas of Massachusetts is barred from doing work until at least Dec. 1 as the state tries to sort out the Sept. 13 Merrimack Gas explosions, while National Grid is under a similar moratorium as a lockout of 1,200 workers enters its fifth month. "This has gone on for a long time and it's having a huge impact," Tamara Small, senior vice president at NAIOP Massachusetts, told State News Service. "There are thousands of units of housing that are affected by this right now. People are calling every day." The gas explosions in the Merrimack Valley killed one and damaged or destroyed 131 buildings in Lawrence, Andover and North Andover. Thousands of customers have been without gas since the explosions, and Columbia Gas has already said it will miss a November 19 deadline to complete restoration work. The moratorium will be in place at least until the Department of Public Utilities completes its investigation. National Grid has been under pressure to end the lockout of its workers. But the moratorium on non-essential gas work was not put into place until a gas line scare in Woburn last month. That left about 300 customers without gas for several days. In both cases, the state has not set a date for when the moratoriums will be lifted. The bans on work do not apply to compliance and emergency work, including the restoration of service in Andover, North Andover and Lawrence. "We've been given no information about when this might end, which complicates everything. There's no certainty in this situation," Mark Leff, senior vice president and construction loan officer at Salem Five Bank and co-chairman of the Home Builders and Remodelers Association of Massachusetts Public Utility Subcommittee, told State News Service. On Tuesday, the state Senate said it would hold hearings starting next month on the gas industry in Massachusetts. The first hearing, on December 4 in Boston, will look at the natural gas industry and infrastructure in Massachusetts. A second hearing of December 17 will be held at an as yet to be determined location in the Merrimack Valley and focus on the disaster and its impact on Andover, North Andover and Lawrence.