Avista owns and operates the historic Post St. substation in downtown Spokane.
To comply with existing permits, the existing river water cooling system was
replaced with a forced-air sytem to cool transformer oil from two generation
transformers and two substation transformers.
Avista choose the design-build delivery model to mitigate risks associated
with retrofitting cooling units in this historic indoor substation, with its
limited working space and energized equipment. Working with a design-build
contractor also allowed Avista to plan outages earlier and compress the overall
completion of the project.
The old river water cooling system discharged, along with leakage through the
foundation, to the tailrace, creating a small waterfall of historical significance.
To preserve the visual aesthetics of this waterfall, additional demolition and site
work was performed inside the substation to collect and direct leakage to the
piping network feeding the waterfall.
MacKay Sposito provided a full-time on-site electrically-qualified inspector to
act as a single point of contact for all parties. This role also included coordination,
quality assurance, and daily reports with progress photos.