ranking first.Continuing with this,over the course of 5 years,every line on our system will be pruned. When we are pruning,we take into account the tree species and weath- er conditions we have in New England to help ensure reliability.Fast-growing species are pruned more judiciously to limit regrowth contacting the lines over the cycle length.Also,pine boughs overhanging our wires are removed or shortened to help prevent failure under snow loading. We also reserve a small amount of funding for Forestry Reliability Assessment work each year.This provides a marginal amount of flexibil- ity to tackle reliability issues that arise mid-year without deviating from our cycle pruning program. Perhaps the largest annual reliability benefit is our Hazard Tree Mitigation component. I believe that the greatest improvement in tree-related reliability comes from removing hazard trees along crit- ical portions of our circuit.We have just implemented a significant hazard tree mitigation program and are expecting to see reliability results from it. Most of our vegetation management programs are designed for
normal weather conditions, such as blue sky days and minor storm events.This year we do have a pilot program aimed at Vegetation Management Storm Resiliency.The goal of this program is to test the effectiveness of reducing tree exposure on reliability during major storm events.We will be removing tree overhang and doing inten- sive hazard tree removal along critical portions of three circuits during this test pilot.
Photos provided by Unitil
Unitil manages the local distribution of electricity and natural gas in the states of New Hampshire, Massachusetts, and Maine.
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Arbor Age / July/August 2012 11
