20240930TARIFF ADVICE NO. INT-TAG-24-02.pdf

RECEIVED
2024 September 30 AM 8:21
INTERMOUNTAIN` IDAHO PUBLIC
GAS COMPANY UTILITIES COMMISSION
A Subsidiary of MDU Resources Group,Inc.
In the Community to Serve®
September 30, 2024
Monica Barrios-Sanchez
Commission Secretary
Idaho Public Utilities Commission
P.O. Box 83720
Boise, ID 83720-0074
RE: Intermountain Gas Company, Case No. INT-TAG-24-02
Dear Ms. Barrios-Sanchez:
Enclosed for filing with this Commission is a copy of Intermountain Gas Company's ("Intermountain" or
"Company") proposed revisions to Section C of its General Service Provisions.The proposed edits to Section
C are presented in Attachment No. 1.The resulting proposed Section C is presented in Attachment No. 2.
The proposed revisions outlined below are in line with Commission Order No. 34735 in Case No. INT-G-20-
01 which authorizes the Company to "file an annual tariff advice to update the Allowable Investment
Factors,the Service Line Cost per Foot, and the construction overhead charge." (See Order No. 34735 at 9.)
1. The update to the Allowable Investment Factors in Section 4.3 includes a change in the compound
inflation factor.
The compound inflation factor is updated to include inflation data for September 2023 through August
2024.The Company adjusts for inflation of the embedded costs from its last general rate case (Case No.
INT-G-22-07)to ensure that new applicants are treated the same as existing customers in terms of the
amount of facilities for which their Allowable Investment will pay.
The calculation of the proposed Allowable Investment Factors, including the adjustments discussed
above, is shown in Attachment No. 3, pages 1-4.
2. The update to its service line cost per foot in Section 5.2 is based on a new three-year average of
service line costs divided by the feet installed during the same years.The proposed three-year average
service line cost per foot is shown in Attachment No. 3, page 5.
3. The change in the construction overhead rate in Section 5.3(c) reflects the Company's currently
calculated rate.

Intermountain Gas Company Page 2 of 2
Case No. INT-TAG-24-02
The Company requests that the proposed revisions become effective one month after Commission approval
to give the Company enough time to implement the changes to its systems and forms.Therefore,the
Company proposes a Commission approval date of November 1, 2024, and an effective date of December
1, 2024.
If you have any questions or require additional information regarding the attached, please contact me at
[phone].
Sincerely,
/s/Lori.A. Blattner
Lori A. Blattner
Director—Regulatory Affairs
Intermountain Gas Company
Enclosures

ATTACHMENT NO. 1
CASE NO. INT-TAG-24-02
INTERMOUNTAIN GAS COMPANY
REDLINE
TARIFF
(2 pages)

IRILI.C. Gas Tariff
Section C IDAHO PUBLIC UTILITIES COMMISSION
evepth^*h Ei hth Revised Sheet No.4 Approved Effective
o utility Intermountain Gas Company Oct. 31, 2023 Dec• 2023
I Jan Noriyuki Secretary
Natural Gas Appliances Annual Therm
Estimates
Range 23
Seasonal Fireplace 50
Grill 15
Clothes Dryer 28
Water Heater 240
(b) For commercial applicants:
The therm usage estimate will be determined by the Company on a case-by-case basis. The
estimate will be based on the climate zone,the heated structure square footage, commercial
property type, and applicable gas appliances.
4.3 To determine the Allowable Investment per applicant, multiply the estimated annual therm usage
per applicant by the applicable Allowable Investment Factor below to calculate the Allowable
Investment in dollars:
Allowable Investment Factors
Customer Type Service Main Combined
Residential 0.6-54674 0.797822 1.4511.496
Commercial 0.486501 0.593612 1.0791.113
4.4 The applicant agrees to install and activate gas appliances pursuant to the signed agreement(s)
and the therm usage estimates used to determine the Allowable Investment.
4.5 The Company may calculate the Allowable Investment for applicants with structures or business
operations which are non-permanent on a case-by-case basis.
5. PROJECT COST
5.1 In the event the Company can defray any of the trench and backfill costs, for example by sharing
a trench with other utilities, the cost reduction will be included in the Main extension cost or
Service cost estimates.
5.2 The Service Line Project Cost estimate is determined by multiplying the on-property Service Line
length by$45.1817.33-per foot.
Issued by: Intermountain Gas Company
By: Lori A. Blattner Title: Director—Regulatory Affairs

Gas Tariff
Section
C IDAHO PUBLIC UTILITIES COMMISSION
Secti
SixthF4fth Revised Sheet No. 5 Approved Effective
Name Intermountain Gas Company Oct. 31, 2023 Dec�2i�
of Utility p Y
5.3 The Main Extension Project Cost estimate is based on the Gas Facilities (excluding Services)
required to serve the gas load of the requesting applicant. This includes but is not limited to
Main, regulator stations, valves and Main fittings.
(a) The Company will provide a Project Cost estimate to the applicant prior to execution of an
agreement.
(b) The estimate will exclude costs for Company Betterment.
(c) The Company includes construction overhead charges in the amount of 10.9791%.
(d) The Main extension Project Cost will be divided by the number of estimated Service Points
to calculate the Main extension Project Cost per applicant.
6. OTHER PAYMENTS
6.1 The Company may require advanced payment from the applicant in the following situations:
(a) As a guarantee when proposed structures and Services are temporary in nature or the gas
load is unpredictable.
(b) When the Company conducts pre-construction engineering studies to improve the accuracy
of cost estimates.
6.2 If an advanced payment is collected according to Section 6.1(a), the Company will refund an
amount equal to the Allowable Investment to customers who meet the terms outlined in the
General Agreement for guaranteed usage. Refunds will not exceed the amount of the advanced
payment.
6.3 If an advanced payment is collected according to Section 6.1(b),and the actual cost of installation
is less than the estimated cost, the difference will be refunded to the customer.
7. VESTED INTEREST AND DEPOSIT REFUNDS
7.1 A customer or developer is eligible for refund of a payment made for Project Costs in excess of
the Allowable Investment for Mains when additional Service Points, not used in the original
calculation or in a previous refund calculation, connect to the Main extension within five years
from installation.
(a) The Company will conduct annual reviews to determine if additional customers have
connected to the Main and turned on gas service.
(b) Intermountain will take the steps outlined in Section 4 to calculate the Allowable Investment
for Mains for each additional customer.
(c) The Company will refund to the original applicant or developer the equivalent of the Allowable
Investment for Mains for each additional customer. Refunds will be made up to the total
upfront payment, but not to exceed the Project Cost in excess of Allowable Investment for
Mains.
Issued by: Intermountain Gas Company
By: Lori A. Blattner Title: Director—Regulatory Affairs

ATTACHMENT NO. 2
CASE NO. INT-TAG-24-02
INTERMOUNTAIN GAS COMPANY
CLEAN
TARIFF
(2 pages)

I.P.U.C. Gas Tariff
Section C
Eighth Revised Sheet No.4
Name Intermountain Gas Company
of Utility
Natural Gas Appliances Annual Therm
Estimates
Range 23
Seasonal Fireplace 50
Grill 15
Clothes Dryer 28
Water Heater 240
(b) For commercial applicants:
The therm usage estimate will be determined by the Company on a case-by-case basis. The
estimate will be based on the climate zone,the heated structure square footage, commercial
property type, and applicable gas appliances.
4.3 To determine the Allowable Investment per applicant, multiply the estimated annual therm usage
per applicant by the applicable Allowable Investment Factor below to calculate the Allowable
Investment in dollars:
Allowable Investment Factors
Customer Type Service Main Combined
Residential 0.674 0.822 1.496
Commercial 0.501 0.612 1.113
4.4 The applicant agrees to install and activate gas appliances pursuant to the signed agreement(s)
and the therm usage estimates used to determine the Allowable Investment.
4.5 The Company may calculate the Allowable Investment for applicants with structures or business
operations which are non-permanent on a case-by-case basis.
5. PROJECT COST
5.1 In the event the Company can defray any of the trench and backfill costs,for example by sharing
a trench with other utilities, the cost reduction will be included in the Main extension cost or
Service cost estimates.
5.2 The Service Line Project Cost estimate is determined by multiplying the on-property Service Line
length by$17.33 per foot.
Issued by: Intermountain Gas Company
By: Lori A. Blattner Title: Director—Regulatory Affairs

I.P.U.C. Gas Tariff
Section C
Sixth Revised Sheet No. 5
Name Intermountain Gas Company
of Utility
5.3 The Main Extension Project Cost estimate is based on the Gas Facilities (excluding Services)
required to serve the gas load of the requesting applicant. This includes but is not limited to
Main, regulator stations, valves and Main fittings.
(a) The Company will provide a Project Cost estimate to the applicant prior to execution of an
agreement.
(b) The estimate will exclude costs for Company Betterment.
(c) The Company includes construction overhead charges in the amount of 10.91%.
(d) The Main extension Project Cost will be divided by the number of estimated Service Points
to calculate the Main extension Project Cost per applicant.
6. OTHER PAYMENTS
6.1 The Company may require advanced payment from the applicant in the following situations:
(a) As a guarantee when proposed structures and Services are temporary in nature or the gas
load is unpredictable.
(b) When the Company conducts pre-construction engineering studies to improve the accuracy
of cost estimates.
6.2 If an advanced payment is collected according to Section 6.1(a), the Company will refund an
amount equal to the Allowable Investment to customers who meet the terms outlined in the
General Agreement for guaranteed usage. Refunds will not exceed the amount of the advanced
payment.
6.3 If an advanced payment is collected according to Section 6.1(b),and the actual cost of installation
is less than the estimated cost, the difference will be refunded to the customer.
7. VESTED INTEREST AND DEPOSIT REFUNDS
7.1 A customer or developer is eligible for refund of a payment made for Project Costs in excess of
the Allowable Investment for Mains when additional Service Points, not used in the original
calculation or in a previous refund calculation, connect to the Main extension within five years
from installation.
(a) The Company will conduct annual reviews to determine if additional customers have
connected to the Main and turned on gas service.
(b) Intermountain will take the steps outlined in Section 4 to calculate the Allowable Investment
for Mains for each additional customer.
(c) The Company will refund to the original applicant or developer the equivalent of the Allowable
Investment for Mains for each additional customer. Refunds will be made up to the total
upfront payment, but not to exceed the Project Cost in excess of Allowable Investment for
Mains.
Issued by: Intermountain Gas Company
By: Lori A. Blattner Title: Director—Regulatory Affairs

ATTACHMENT NO. 3
CASE NO. INT-TAG-24-02
INTERMOUNTAIN GAS COMPANY
ALLOWABLE
INVESTMENT
CALCULATIONS
(5 pages)

Attachment No.3
Case No.INT-TAG-24-02
INTERMOUNTAIN GAS COMPANY Intermountain Gas Company
Page 1 of 5
Line Extension Allowable Investment Factors
Line No. Description Residential Commercial
(a) (b) (c)
1 Services Allowable Investment Factor
2 Service Line Extension Embedded Cost per Therm:
3 FERC Account 380111 $ 0.041712 $ 0.031019
4 FERC Account 385121 0.002575 0.001915
5 Total $ 0.044287 $ 0.032934
6 Compound Inflation Factor131 108.5% 108.5%
7 Service Line Extension Embedded Cost per Therm(Line 5 times Line 6) $ 0.048038 $ 0.035723
8 Weighted Asset Life:
9 FERC Account 380-Asset Life141 58 58
10 FERC Account 380-Embedded Cost per Therm"' $ 0.041712 $ 0.031019
11 Weighting Factor(Line 9 times Line 10) 2.419315 1.799122
12 FERC Account 385-Asset Life"' 40 40
13 FERC Account 385-Embedded Cost per Therm"' $ 0.002575 $ 0.001915
14 Weighting Factor(Line 12 times Line 13) 0.103007 0.076601
15 Weighted Asset Life(Sum of Lines 11 and 14 divided by Line 5) 57.0 57.0
16 Weighted Average Cost of Capital El 6.97% 6.97
17 Services Allowable Investment Factor($/therm)171 $ 0.674 $ 0.501
18 Mains Allowable Investment Factor
19 Main Line Extension Embedded Cost per Therm:
20 FERC Account 374181 $ 0.000408 $ 0.000304
21 FERC Account 376191 0.050406 0.037485
22 FERC Account 3781101 0.002557 0.001901
23 Total $ 0.053371 $ 0.039690
24 Compound Inflation Factor131 108.5% 108.5%
25 Main Line Extension Embedded Cost per Therm(Line 23 times Line 24) $ 0.057891 $ 0.043051
26 Weighted Asset Life:
27 FERC Account 374-Asset Life"" 56 56
28 FERC Account 374-Embedded Cost per Therml8l $ 0.000408 $ 0.000304
29 Weighting Factor(Line 27 times Line 28) 0.022865 0.017003
30 FERC Account 376-Asset Life1��1 70 70
31 FERC Account 376-Embedded Cost per Therm"' $ 0.050406 $ 0.037485
32 Weighting Factor(Line 30 times Line 31) 3.528446 2.623926
33 FERC Account 378-Asset Life1�31 43 43
34 FERC Account 378-Embedded Cost per Therm"' $ 0.002557 $ 0.001901
35 Weighting Factor(Line 33 times Line 34) 0.109937 0.081754
36 Weighted Asset Life(Sum of Lines 29,32 and 35 divided by Line 23) 68.6 68.6
37 Weighted Average Cost of Capital 161 6.97% 6.97
38 Mains Allowable Investment Factor($/therm)1141 $ 0.822 $ 0.612
NOTES
111 See Attachment No.3,Page 3,Lines 6 and 16,Column(g)
r2]See Attachment No.3,Page 3,Lines 9 and 19,Column(g)
l3]See Attachment No.3,Page 4,Line 3,Column(n)
141See Attachment No.3,Page 3,Lines 6 and 16,Column(b)
151See Attachment No.3,Page 3,Lines 9 and 19,Column(b)
lsl Case No.INT-G-22-07,Stipulation and Settlement,Exhibit No.1
pl The present value of Line 7 discounted by the weighted average cost of capital on Line 16 over the weighted life of
the assets on Line 15
la]See Attachment No.3,Page 3,Lines 2 and 12,Column(g)
p]See Attachment No.3,Page 3,Lines 4 and 14,Column(g)
1101 See Attachment No.3,Page 3,Lines 5 and 15,Column(g)
11+] See Attachment No.3,Page 3,Lines 2 and 12,Column(b)
1121 See Attachment No.3,Page 3,Lines 4 and 14,Column(b)
1131 See Attachment No.3,Page 3,Lines 5 and 15,Column(b)
1141 The present value of Line 25 discounted by the weighted average cost of capital on Line 37 over the weighted
life of the assets on Line 36

Attachment No.3
Case No. INT-TAG-24-02
Intermountain Gas Company
INTERMOUNTAIN GAS COMPANY Page 2 of 5
Class Line Extension Embedded Costs
Line No. Description Total Company Residential Commercial
(a) (b) (c) (d)
1 Line Extension Costs Embedded in Current Rates
2 Case No.INT-G-22-07 Commission Ordered Depreciation $ 22,007,089
3 Case No.INT-G-22-07 Commission Ordered Operating Income at 6.97% ' 26,854,614
4 Tax Gross-UpI'l 9,392,938
5 Line Extension Embedded Costs(Sum of Lines 2-4) $ 58,254,641
6 Class Allocation of Line Extension Embedded Costs
7 Case No.INT-G-22-07 Proposed Distribution&Customer Rate Base 131 $ 334,701,962
8 Case No.INT-G-22-07 Commission Ordered Rate Base Ill 385,288,577
9 Proposed Distribution Rate Base Percentage(Line 7 divided by Line 8) 86.87%
10 Case No.INT-G-22-07 Class Base Revenue Requirement[21 $ 73,360,477 $ 26,811,471
11 Case No.INT-G-22-07 Total Base Revenue Requirement[21 111,398,580 111,398,580
12 Class Base Revenue Requirement Percentage(Line 10 divided by Line 11) 65.85% 24.07%
13 Class Line Extension Embedded Costs[4] $ 33,326,150 $ 12,179,898
NOTES
Ill Case No.INT-G-22-07,Stipulation and Settlement,Exhibit No.1
[21 Case No.INT-G-22-07,Stipulation and Settlement,Exhibit No.2
[3I Case No.INT-G-22-07,R.Amen Exhibit No.2-Update,Page 32
141 Line 5,Column(b)times Line 9,Column(b)times Line 12 Columns(c)and(d),respectively.

Attachment No.3
Case No. INT-TAG-24-02
INTERMOUNTAIN GAS COMPANY Intermountain Gas Company
Line Extension Embedded Cost per Therm by Distribution Account Page 3 of 5
Total Company Total Company Class Line Extension Class Billing Class Line Extension
Depreciation Distribution Plant in Embedded Cost by Determinants Embedded Cost per Therm
Line No. Description WWI Service121 %by Account Account131 (Therms)141 by Accountlsl
(a) (b) (c) (d) (e) M (g)
1 Residential
2 FERC Account 374-Dist Land&Land Rights 56 $ 2,102,230 0.35% $ 116,273 284,776,158 $0.000408
3 FERC Account 375-Dist Structures&Improvements 53 96,343 0.02% 5,329 284,776,158 $0.000019
4 FERC Account 376-Dist Mains 70 259,532,576 43.07% 14,354,531 284,776,158 $0.050406
5 FERC Account 378-Dist Meas&Reg Sta Equip-Gen 43 13,163,797 2.18% 728,079 284,776,158 $0.002557
6 FERC Account 380-Dist Services 58 214,768,642 35.64% 11,878,675 284,776,158 $0.041712
7 FERC Account 381-Dist Meters 48 80,614,323 13.38% 4,458,711 284,776,158 $0.015657
8 FERC Account 383-Dist House Regulators 50 19,006,002 3.15% 1,051,206 284,776,158 $0.003691
9 FERC Account 385-Dist Ind Reg Sta 40 13,259,048 2.20% 733,347 284,776,158 $0.002575
10 Total $ 602,542,961 100.00% $ 33,326,150
11 Commercial
12 FERC Account 374-Dist Land&Land Rights 56 $ 2,102,230 0.35% $ 42,495 139,956,787 $0.000304
13 FERC Account 375-Dist Structures&Improvements 53 96,343 0.02% 1,947 139,956,787 $0.000014
14 FERC Account 376-Dist Mains 70 259,532,576 43.07% 5,246,232 139,956,787 $0.037485
15 FERC Account 378-Dist Meas&Reg Sta Equip-Gen 43 13,163,797 2.18% 266,095 139,956,787 $0.001901
16 FERC Account 380-Dist Services 58 214,768,642 35.64% 4,341,367 139,956,787 $0.031019
17 FERC Account 381-Dist Meters 48 80,614,323 13.38% 1,629,551 139,956,787 $0.011643
18 FERC Account 383-Dist House Regulators 50 19,006,002 3.15% 384,190 139,956,787 $0.002745
19 FERC Account 385-Dist Ind Reg Sta 40 13,259,048 2.20% 268,020 139,956,787 $0.001915
20 Total $ 602,542,961 100.00% $ 12,179,898
NOTES
11I Case No.INT-G-21-01,Stipulation and Settlement,Settlement Exhibit No.1,Page 1,Lines 19-30,Column(m)
[21 Case No.INT-G-22-07,R.Amen Exhibit No.2-Update,Page 23
l31 Column(d)times Attachment No.3,Page 2,Line 13,Columns(c)and(d),respectively
[41 Case No.INT-G-22-07,Stipulation and Settlement,Exhibit No.3
[51 Column(a)divided by Column(q

Attachment No.3
Case No. INT-TAG-24-02
INTERMOUNTAIN GAS COMPANN Intermountain Gas Company
U.S.Inflation Datal'] Page 4 of 5
Line No. Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Inflation Factor
(a) (b) (c) (d) (e) (f) (g) (h) (i) Q) (k) (1) (m) (n)
1 2023 5.6% 5.5% 5.6% 5.5% 5.3% 4.8% 4.7% 4.3% 4.1% 4.0% 4.0% 3.9% 104.8% [2]
2 2024 3.9% 3.8% 3.8% 3.6% 3.4% 3.3% 3.2% 3.2% 103.5% [2]
3 Two Year Compound Inflation Factor 108.5% [31
NOTES
I']Inflation data obtained from the Bureau of Labor Statistics website:https://data.bis.gov/timesedes/CUUROOOOSAOLlE?output view=pct_12mths
121 One plus the average of Columns(b)-(m)
131 Column(n),Line 1 times the inflation factor for each year since the last rate case

Attachment No.3
Case No. INT-TAG-24-02
INTERMOUNTAIN GAS COMPANY Intermountain Gas Company
Average Cost per Foot for Service Lines Page 5 of 5
Line
No. Description 2020 2021 2022 Average
(a) (b) (c) (d) (e)
1 FERC Account 380 Additions $ 13,034,296.25 $ 15,164,511.24 $ 18,351,455.89 $ 46,550,263.38
2 Feet Installed 862,755 965,058 858,487 2,686,300
3 Cost/Foot $ 15.11 $ 15.71 $ 21.38 $ 17.33