Unitil’s electric service will be spraying chemical herbicide around 6.7 miles of off-road power lines in north Concord next month, and adjoining property owners have the option of declining their use if they have concerns about drinking water or environmentally sensitive areas.

The program is expected to start Oct. 7, and will cover two stretches of what are known as sub-transmission lines. One section runs parallel to I-93, starting near the I-393 interchange, and the other is similar but slightly farther west. They run mostly through wooded areas, not along roads.

Workers will apply one or more of several herbicides from backpack sprayers, targeting trees getting tall enough to pose a problem with the lines, and targeting invasive plants that might be spread to new areas if they were cut with commercial mowing machines, according to Alec O’Meara, Unitil spokesman.

“They go in with a backpack that has the application and go plant by plant, apply it directly to plants,” he said. “This is work we use only in very specific areas – off-road right-of-ways – where we can take a much more targeted approach ... than broad-based mowing.”

Owners of property abutting the rights of way will be notified and can request that the work be done by cutting rather than spraying next to their property, O’Meara said. The company statement notes that property owners can also notify Unitil if they have concerns about wells or “any other environmentally sensitive areas where herbicide application should be further restricted” by calling Sara Sankowich, Unitil arborist, at 379-3833.

Herbicides that may be used are glyphosate; triclopyr; imazapyr; and metsulfuron methyl. O’Meara said sprays may also use a surfactant, which helps the pesticide stick to plants and get ingested.

The spraying will last as long as necessary, largely dependent on weather. The material cannot be applied when it is too windy or raining.

The practice of spraying chemicals is fairly common for utilities to keep vegetation down under wires. The transmission lines are in 50-foot-wide rights of way, carried on poles with crossbars up to 10 feet wide. “They are a little bigger than what is on the side of the street,” O’Meara said.

The lines carry electricity at 16 or 34.5 kilovolts, reduced in power from the levels of cross-country transmission lines, but still stronger than the electricity carried on street-side distribution lines.

(David Brooks can be reached at 369-3313 or dbrooks@cmonitor.com or on Twitter @GraniteGeek.)]]>