20190827Avista to Staff 144.pdf

ldaho Public Utilities Commission
Olfice ol the SecretaryAVISTACORPORATION RECEIVED
RESPONSE rO REQUEST FoR rNFoRMArroN AUG 2 7 20lg
JURISDICTION:
CASE NO:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff-144
DATE PREPARED
WITNESS:
RESPONDER:
DEPARTMENT:
TELEPHONE:
08l26l20l9Bohe, ldaho
Heather Rosentrater
Zachary Curry
Substation
(s09) 49s-8922
REQUEST:
Please provide a list of substations included in the Business Case Narrative for the Substation
Rebuilds Program. Please detail the proposed work to be performed with dates, and include
descriptions and cost estimates. Rosentrater Schedule 3 at66.
RESPONSE:
A summary of the projects that are included in the Company's updated capital adjustment that was
provided in response to Staff PR_067 follows:
A brief description of the three major projects follows:
Westside Rebuild
Westside substation was built in the 1970s and has equipment that has reached end of life. A
brownfield rebuild was decided to be performed after other alternatives were considered. This
project, (with a total costs of approximately $4.55 million) is broken into 5 phases of work and are
declared used and useful at the end of each phase of the project. Sections of the substation will
remain energized for the duration of the rebuild. One portion of the aforementioned work is
included in the substation rebuilds business case - the Westside Auto #2 project, which includes
procurement of a second 250MVA, 230-ll5kV autotransformer, associated labor and design, and
a few smaller bits of work connected to the Westside rebuild. This portion of the project is
approximately $ 1.26 million.
d
m ldaho
Distribution Detail
Priest River Rebuild
Kamiah Rebuild
Various Small ldaho Projects
Tota I Distribution
Total Substation Rebuild Business Case
-i
S 4,947
(Sooosl
s S
60
9 722
pdatedFiled U
S+798s
735
Filed
5 7,107
7,399
Tra nsmission
Distribution
Transmission Detail
Westside Rebuild
U pdated
s 3,582 s 2,163 s 1,260
7,002
356
2,329
3,687
Priest River Rebuild
The station breaker for this site was at end of life and the distribution structure was inherited
during purchase from PP&L with a low-hanging bus. Replacing the old breaker in place was not an
option due to low clearances. The regulation was achieved using a 3-phase regulator which was the
last on our system, and known to fail catastrophically. In 2016, a temporary station viper recloser
and temporary feeder regulators were installed before the breaker had to be put through another
winter. In order to prepare for the distribution rebuild, temporary power, control, and
communications cables were run in above ground PVC from field equipment to the panel house.
This design also utilizes insulated mobile cables from the transformer to the viper which are laying
on the ground. Minor rebuild of distribution was recommended because the temporary viper and
regulation had already been installed to facilitate the rebuild. Above-ground PVC cabling was
meant to be temporary and was not to be considered a permanent solution. Minor rebuild was
performed including replacing a feeder, oil circuit breaker, regs, and increase station to two UG
feeders. Also included removal of cap bank, replacement of fence, and yard expansion to facilitate
installing an emergency mobile sub in the event it is needed. Project cost is approximately $1
million.
Kamiah Rebuild
Kamiah Substation needed rebuilt for a variety of reasons. The original wood structures had
deteriorated severely. The existing location had poor soil and groundwater issues which have
contributed to structures leaning away from plumb. Wood crossarms were in danger of imminent
failure. Equipment problem started to crop up, including the failure of the sudden pressure
relaying circuit on the transformer. Feeder reclosers are no longer supported from a manufacturer
standpoint. After considering alternatives, the decision was made to construct a new 115/13kV
substation w/circuit switcher, power transformer, three feeders, and SCADA on a new property.
The 2019 transfers to plant represent trailing charges for this project that was completed in late
2018. The total project costs are approximately $2.0 million.