By a narrow majority, the Devens Enterprise Commission (DEC) agreed last week to reconsider the protocol approved last December to measure whether noise coming from the Evergreen Solar plant at Devens complies with DEC rules.

The margin in favor was 6-5, the first time in anyone’s memory that commission members were so closely divided on an issue before them. Chairman William Marshall cast the tie-breaking vote. Commissioners Jim deZutter and Erik Stoltz, who represent Harvard on the DEC, both voted in favor of the resolution.

The question before the DEC was not whether its methodology for measuring sound at the Evergreen plant is correct, but whether the amount of noise permitted at two sound monitors is set low enough to keep the din in Harvard at permitted levels.

The current protocol was approved by the DEC last year, but Harvard residents, backed by the Harvard Board of Selectmen, immediately objected, arguing that the DEC had acted hastily and had not allowed enough time for public input. In a series of meetings over the past six months, DEC commissioners have heard testimony from lawyers, sound consultants, and residents representing the DEC, Evergreen, and residents of Old Mill Road in Harvard. Evergreen has maintained throughout that the present protocol is correct and that the factory is in compliance. Residents have argued that the protocol is flawed. More recently, a new consultant hired by DEC has appeared to side with the Harvard abutters and has proposed that DEC leave its protocol in place, but set a lower decibel limit at the plant—a so-called “bright line”—that would remove any uncertainty over whether Evergreen is quiet enough.

The next step is for the DEC’s staff and consultant to prepare options for the commission. DEC commissioners will likely be asked to choose among three possibilities: keep the current limits, choose the “bright line” limits proposed by its consultant, or allow Evergreen to operate in a “grey zone,” in which case complaints would have to be resolved case by case.

Harvard’s long-suffering abutters favor a “bright line” and believe the sound levels it sets for the plant will protect them. If DEC adopts that option, says Jay Wallace, of Old Mill Road and co-owner of Dunroven Farm, “We’re done.”