The Department of Environmental Protection granted Fox Islands Wind a two-month extension to file a revised operation protocol for the Vinalhaven wind turbines, according to James Cassida, the DEP’s director of the Division of Land Resource Regulation.

The DEP requested the revised protocol in a Nov. 23 letter to Fox Islands Wind. The letter described a noise complaint that alleged Fox Islands Wind failed to comply with the 45 decibel nighttime noise limit for a specific period in July 2010.

In the letter, the DEP said it confirmed that during that specific time periods, Fox Islands Wind was operating with a sound output of 47 decibels.

“Further analysis of the operational, sound, and meteorological data collected during the complaint period, as well as other data collected during the period of May 1, 2010 to Aug. 31, 2010, indicate that, at current operation levels, the facility is likely to exceed the required sound compliance level of 45 dBA when there is significant vertical and directional wind shear,” the DEP’s letter said.

The DEP requested that Fox Islands Wind submit an outline in December for its revised operation protocol. Fox Islands Wind did submit that outline in early December. Fox Islands Wind’s proposed protocol called for slowing down the turbines to reduce the noise level when the wind direction is out of the southwest and the surface level wind speeds are less than 6 mph.

A few weeks later, the DEP provided feedback and asked for more data and a trigger based on wind shear to slow down the turbines and reduce the noise level. Wind shear is caused when the wind blows at different speeds at the ground and higher altitudes, such as several hundred feet above the ground where the turbine blades spin.

The DEP requested a revised operation protocol by Jan. 23. Prior to that deadline, Fox Islands Wind requested, and the DEP approved, a two-month extension for the revised operations protocol, Cassida said.

On Jan. 28, Cassida said the DEP and Fox Islands Wind are having discussions on the feedback and working to resolve the issues with the wind shear trigger.