The Bureau of Reclamation is extending the public comment period for a proposed multi-year powerplant overhaul project at two Grand Coulee Dam powerhouses.

The initial 30-day comment period ended Nov. 7; however, at the public’s request, it has been extended to Nov. 21.

Reclamation is requesting public and agency input to help identify issues to be addressed in an environmental assessment for the proposed project to overhaul the 18 generating units in the left and right powerhouses.

The 18 generating units and three station service units have been in operation for over 70 years and are starting to have mechanical problems from age-related wear and design, a press release from Reclamation said. The agency would upgrade components of the generating units, modernize three station service generators, conduct maintenance pageof the penstocks, and update or replace the overhead cranes.

The project scope includes new generator winding and stator cores for the main unit generators; new static digital excitation systems; digital governor control systems; local unit controls and generator relay protection systems; penstock lining repair or replacement; replacement or modernization of the nine crane servicing the powerhouses; modernization of three station service generators in the left powerhouse; and replacement or refurbishment of the iso-phase bus and circuit breakers.

Reclamation is considering alternatives including no action, working on two units at a time, or modernization and overhauling just one unit at a time. The two-at-a-time scenario would start in the spring of 2018 and finish in 2029. The one-at-a-time option could extend the work up to seven years.

Interested parties can submit comments to: Pam Druliner, Natural Resource Specialist, Bureau of Reclamation, 1150 North Curtis Road, Boise, Idaho, 83706; or by emailing pdruliner@usbr.gov