20160823AVU to Staff 92.doc

AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION

JURISDICTION: IDAHO DATE PREPARED: 08/17/2016
CASE NO.: AVU-E-16-03 WITNESS: Bryan A. Cox
REQUESTER: IPUC RESPONDER: David Machado
TYPE: Production Request DEPARTMENT: State & Federal Regulation
REQUEST NO.: Staff - 092 TELEPHONE: [phone]

REQUEST:

Please explain the method and justification used to jurisdictionally allocate the $2,525,000 cost of improvement assets related to the Westside (Substation) Rebuild Phase I project discussed in Bryan Cox’s Direct Testimony (pp. 28 -29).

RESPONSE:

As shown on page 10 of the 2015 Avista System Planning Assessment, provided with the Company’s response to Staff_PR_106 Attachment B, the Westside Station is part of Avista’s 230 kV transmission system. As discussed in the Company’s response to Staff_PR_105, Avista’s transmission system is described in Avista’s 2015 Electric IRP in the following way, “The transmission system operates distinctly from the distribution system. For example, the transmission system is a network linking multiple sources with multiple loads, while the distribution system configuration uses radial feeders to link a single source to multiple loads.”

Because the transmission network supports customer loads in both Idaho and Washington, Avista uses the P/T (production/transmission) ratio (see the Company’s response to Staff_PR_105 for further information about the calculation of the P/T ratio) to allocate its transmission plant investments between Idaho and Washington. As the Westside station is a component of Avista’s broader transmission system, the investment in the Westside Rebuild Phase I was allocated between Idaho and Washington using the current P/T ratio of 34.370% for Idaho and 65.630% for Washington.

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