FSEC posts addendum on Horse Heaven Wind micrositing; staff say most changes fall within prior FEIS scope

FSEC staff reported on July 15 that it posted an addendum to the Horse Heaven Wind final environmental impact statement addressing micrositing updates from the certificate holder. The addendum documents seven principal updates, among them a commitment to turbine option 2 (maximum blade tip height up to 671 feet), a reduction in total turbines from 147 to 116 under the certificate holder’s preferred layout, routing adjustments confined to the micrositing corridor, relocation of some substations and switchyards (no increase in footprint), a possible elimination of a planned adjacent switchyard, and a conversion of one interstate transmission crossing from underground to overhead.

Staff received 107 public comments on the addendum. Sean Green, FSEC SEPA specialist, told the council that while members of the public asked for supplemental EIS work to address taller turbines or other adjustments, the FEIS had already evaluated both option 1 (shorter turbines) and option 2 (taller turbines) and those options were included in the executed site certification agreement; staff concluded that most of the micrositing updates do not represent new or increased impacts beyond the FEIS evaluation. The one exception staff highlighted was the change from an underground interstate crossing to an overhead crossing; staff said the addendum addressed that change as a nonsignificant impact.

No council action was required on the addendum; the next council action that will consider these findings will come later in the process when the council considers final construction plans.