20210326Staff 6-10 to INT.pdf

DAYN HARDIE
DEPUTY ATTORNEY GENERAL
IDAHO PUBLIC UTILITIES COMMISSION
PO BOX 83720
BOISE, IDAHO 83720.0074
[phone]
IDAHO BAR NO. 9917
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Street Address for Express Mail:
472W. WASHINGTON
BOISE, IDAHO 83702.5918
Attorney for the Commission Staff
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
IN THE MATTER OF INTERMOUNTAIN GAS
COMPANY'S APPLICATION FOR APPROVAL
TO CHANGE DEPRECIATION AND
AMORTIZATION RATES
CASE NO. INT-G.2I-01
SECOND PRODUCTION
REQUEST OF THE
COMMISSION STAFF TO
INTERMOUNTAIN GAS
COMPANY
The Staff of the Idaho Public Utilities Commission, by and through its attorney of record,
Dayn Hardie, Deputy Attorney General, request that Intermountain Gas Company (Company)
provide the following documents and information as soon as possible, or by FRIDAY,
APRrL 16,2021.
This Production Request is continuing, and the Company is requested to provide, by way of
supplementary responses, additional documents that it, or any person acting on its behalf, may later
obtain that will augment the documents produced.
Please provide answers to each question, supporting workpapers that provide detail or are
the source of information used in calculations. The Company is reminded that responses, pursuant
to Commission Rules of Procedure, must include the name and phone number of the person
preparing the document, and the name, location, and phone number of the record holder, and if
different, the witness who can sponsor the answer at hearing if need be. Reference IDAPA
31.01.01.228.
SECOND PRODUCTION REQUEST
TO INTERMOUNTAIN GAS MARCH 26,2021
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with formulas activated.
REQUEST NO. 6: In Section 3.4 of its Depreciation Study, Concentric states that it uses a
residual measure based on a least squares solution of the difference between the stub curve and the
survivor curve. Please confirm that the following equation describes this residual measure:
restdua.lmeasttre =f,1(data; - cur$€i)2
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where datai is the ith data point, ctttr€i is the corresponding point from the survivor curve, and r is
the number of data points used in the computation. If this equation does not correctly describe the
residual measure as described in Section3.4, please provide a corrected equation with explanation
of the variables used in it.
REQUEST NO. 7: In Section 3.4 of its Depreciation Study, Concentric states, "This
Residual Measure is based on a least squared solution of the differences between the stub curve (or
original data points) and smooth survivor curve, which also requires a balancing of the differences
above and below the stub curve." Please explain how this balancing is performed.
REQUEST NO. 8: In its Depreciation Study, Concentric evaluates the fit of several
survivor curves using the residual measure. For example, when evaluating the curve fit for account
367 (Transmission Mains) in Section 3.5.1, the Company states, "The recommended retirement rate
analysis provides a statistical residual measure of 1.842 which indicates a good fit." Please answer
the following questions:
a. What values of the residual measure does Concentric take to indicate a good fit?
b. What values of the residual measure does Concentric take to indicate a poor fit?
c. How did Concentric determine the criteria used to judge whether the fit is good or
poor?
SECOND PRODUCTION REQUEST
TO INTERMOUNTAIN GAS MARCH 26,20212
In addition to the written copies provided as response to the questions below, please provide
all reouested charts- tahles^ and workoaoers in their native electronic file format (i e F,xcel)- on CD
REQUEST NO. 9: Pages 6-23 through6-26 of Concentric's Depreciation Study provide
the data and survivor curve for Account 367.00, Transmission Mains. For this account, Concentric
chose a 58-R3 survivor curve. According to Section 5.2,the first numeral (58) indicates the average
life estimated from curve fiUing. Please explain how, given that92.79Yo of the plant in account
367.00 was still in service at 58 years Concentric chose the 58-R3 curve.
REQUEST NO. 10: Pages 6-30 through6-32 of Concentric's Depreciation Study provide
the data and survivor curve for Account 370.00, Transmission-Communication Equipment.
According to this data,l00o/o of the equipment in this account was still in service at 47.5 years.
Please explain how Concentric fit this data to a curve with a 35-year average life.
DATED at Boise, Idaho, this 2(h day of March2D2l.
Dayn
Deputy Attomey General
i:umisc:prodreq/intg2l.ldh prod req2
SECOND PRODUCTION REQUEST
TO INTERMOUNTAIN GAS J MARCH 26,2027
CERTIFICATE OF SERVICE
I HEREBY CERTIFY THAT I HAVE THIS 26TH DAY OF MARCH 2021,
SERVED THE FOREGOING SECOND PRODUCTION REQUEST OF THE
COMMISSION STAFF TO INTERMOUNTAIN GAS COMPAI\"Y, IN CASE NO
INT-G-21.01, BY E.MAILING A COPY THEREOF, TO THE FOLLOWNG:
LORI BLATTNER
DIR _ REGULATORY AFFAIRS
INTERMOUNTAIN GAS CO
PO BOX 7608
BOISE ID 83707
E-MAIL : [e-mail]
PRESTON N CARTER
GIVENS PURSLEY LLP
601 W BANNOCK ST
BOISE ID 83702
E-MAIL : prestoncarter@ givenspursley.com
kendrah@ eivenspursley. com
SECRETAR
CERTIFICATE OF SERVICE