Unitil continues to conduct line work on the 69 kilovolt (kV) sub-transmission lines located within off-road rights-of-way (ROWs) in the communities of Fitchburg, Lunenburg, and Townsend, Massachusetts. This line work replaces the existing static wire, which is nearing the end of its useful service life. The ROWs associated with this line work, though, cross a number of wetlands, streams, and waterbodies. As a result, Unitil is managing the environmental aspects of the static wire replacement project from the planning phase to ensure that its environmental impact is minimized.
Project Update: October 19, 2011 (Wednesday) - Work had been progressing as anticipated up until Tropical Storm Irene's impact in late August/early September. Although Unitil was able to restore power quickly in the wake of Irene, internal and external resources were committed to the restoration efforts of other utilities during the subsequent week. And since mid-September, the local region has been impacted by a number of storm events, many of which included heavy rainfall. As a result, work has been slowed and a delay in the overall project completion has been incurred.
Through mid-November 2011, USA crews will be working on the 08 Line as it splits from the 09 Line in Lunenburg and crosses into Townsend, roughly paralleling RT 13 and ending at the Townsend 15 Substation off Main Street. If the weather remains favorable during this time period, USA crews may also complete work on the 08 line in Lunenburg as it traverses Lanni Orchards near RT 13, which was postponed intentionally due to the apple harvest season.
An environmental presentation has been prepared on the static wire replacement project, which further describes the project's statistics and available BMPs.
What is static wire?
The static wire is a pole's (or structure's) topmost wire, and it directs voltage surges caused by lightning strikes off the power lines . While this wire is essential for sub-transmission lines, it is rarely used on distribution lines. Without the static wire, lightning-induced voltage would build up on the power lines and cause damage to the electric delivery system. The static wire directs the voltage surges to ground by its frequent connections to the grounding conductor.
What type of line work will be done?
The line crews are visiting each pole twice during the project. The first visit transfers the old static wire to temporary supports mounted to the pole called a running block. Once a significant length of the old wire has been transferred, the new wire is attached to one end of the old wire and pulled through the running blocks to the other end, much like the successive threading of multiple needles. The second visit then transfers the new wire from the running blocks to the poles for final attachment. This process flow removes the need to drag wire across the floor of the ROWs, which would otherwise result in a greater impact to the environment.
What environmental concerns exist with the line work?
Where each pole is visited twice, the line crews need to access the entire length of the ROWs. Although access roadways are present along most of the ROWs, some portions are impassable because of the presence of sensitive receptors. These receptors are often present as low-lying land or priority habitat for threatened or endangered plants and animals. For these portions of the ROWs, the line crews either use best management practices (BMPs) to cross the receptors or limit access to them by implementing pole climbing methods only and forgo the use of mechanized equipment.
What measures will be used to protect the environment?
BMPs are engineering controls designed specifically to limit the impact an activity has on a sensitive receptor. Examples of BMPs include: silt fences, hay bales, and hay mulching for soil erosion control, swamp mats for vehicle movement over wetlands, and gravel pads for road turnouts to prevent off-road rutting. Also, a wetlands specialist has been retained for the duration of the project to conduct weekly inspections of the line work, confirming adherence to the BMPs and identifying the presence of sensitive receptors in advance of the work in them. Lastly, communications with the respective conservation commissions is ongoing to ensure that local, environmental concerns are addressed.
When will the line work be completed?
Line work commenced in mid-July 2011 and activities in Fitchburg have been completed. At present (mid-October 2011), about 50 percent of the project has been completed. Ongoing work remains in Lunenburg and Townsend. Provided the weather remains seasonable, Unitil anticipates completing the project in early January 2012. Understandably, though, weather events may impact the anticipated completion. Images collected during the project may be viewed on Unitil's flickr account.