20160823AVU to Staff 105.doc

AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION

JURISDICTION: IDAHO DATE PREPARED: 08/19/2016
CASE NO.: AVU-E-16-03 WITNESS: Bryan Cox
REQUESTER: IPUC RESPONDER: David Machado
TYPE: Production Request DEPARTMENT: State & Federal Regulation
REQUEST NO.: Staff - 105 TELEPHONE: [phone]

REQUEST:

Please provide the Idaho customer load served by each of the individual transmission investments summarized in Mr. Cox’s Direct Testimony.

RESPONSE:

Avista’s 2015 Electric IRP, at page 8-1, describes the transmission system 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.” Given that the transmission system operates in this network fashion, where multiple sources are linked with multiple loads, the assignment of specific customer loads to specific transmission investments is not practicable. Avista calculates the P/T (production/transmission) ratio on an annual basis to reflect the jurisdictional proportion of load between Idaho and Washington. The P/T ratio is based upon an equal weighting of the relative percentages between Idaho and Washington of retail energy sales and of peak megawatts. Therefore, this ratio is representative of the relative use of the transmission network between jurisdictions. The P/T ratio is currently 65.630% for Washington to 34.370% for Idaho.

With regard to the individual transmission investments summarized in Mr. Cox’s direct testimony, the majority of the investments are transmission investments common to all jurisdictions served by the transmission network. The customer load served by each of these investments is best represented by the P/T ratio discussed above.

Certain other investments, particularly the “SCADA – System Operations and Backup Control Center,” “SCADA Completion,” and “Substation – Station Rebuilds” investments are somewhat different from the other transmission investments. The SCADA investments do not directly serve customer load; rather, they enable system control and meet regulatory requirements and are, in fact, common to all jurisdictions and services served by Avista. The “Substation – Station Rebuilds” business case is unique in that substations contain both transmission-related and distribution-related investments. However, both components were included in Mr. Cox’s testimony to avoid repetition of the description of the business case. The customer load associated with the transmission-related substation investments are considered in the same way as any other transmission investment, as discussed above. The customer load associated with the distribution-related substation investments is directly assignable. The distribution-related substation investment originally included within this business case for the Idaho jurisdiction is related to the Kamiah, South Lewiston, and Dalton Gardens substations. However, the Dalton Gardens substation project has been delayed until the 2018/2019 time frame (this delay will be reflected in the updated expected transfer to plant balances provided in Avista’s response to Staff_PR_140).

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