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Home My WebLink About20251223Exhibit 6.pdf Intermountain Gas Company Capacity Enhancement Alternatives NPV by AOI 2025 — 2030 INTEPAOUNTAIN `�' GAS COMPANY A Subsidiary of MDU Resources Group, Inc. In the Community to Serve' Exhibit No. 6 Intermountain Gas Company Ada County AOI Net Present Value Alternative# Alternative Description Details O&M Cost Used for NPV Net Present Value Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 N/A New Plymouth Gate Upgrade Facility N/A ($3,477,264) $ (3,640,000) $ $ $ $ $ $ $ Year 8 Year 9 Year 30 Year 11 Year 12 Year 13 Year 14 Year 15 Year 16 Year 17 Year 18 Year 19 Year 20 S $ $ $ 5 $ $ $ $ $ $ $ $ Alternative# Alternative Description Details O&M Cost Used for NPV Net Present Value Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 N/A State Penn Gate Upgrade IFacility N/A 1 ($2,846,771) $ (2,980,000) $ $ $ $ $ $ 5 Year 8 1 Year 9 Year 30 Year 11 1 Year 12 Year 13 Year 14 Year 15 Year 16 Year 17 Year 18 Year 19 Year 20 $ $ $ $ 1$ $ $ $ $ $ $ $ $ Alternative N Alternative Description Details O&M Cost Used for NPV Net Present Value Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Distribution O&M per mile of N/A Caldwell Reinforcement 5.06 miles-6 inch DP pipe added ($3,572,906) $ (3,650,000) $ (14,547) $ (14,838) $ (15,135) $ (15,438) $ (15,746) $ (16,061) $ (16,383) Year 8 Year 9 Year 30 Year 11 Year 12 Year 13 Year 14 Year 15 Year 16 Year 17 Year 18 Year 19 Year 20 $ (16,710) $ (17,044) $ (17,385) $ (17,733) $ (18,088) $ (18,449) $ (18,818) $ (19,195) $ (19,579) $ (19,970) $ (20,370) $ (20,777) $ (21,193) 2 Intermountain Gas Company State Street AOI Net Present Value Alternative a Alternative Description Details O&M Cost Used for NPV Net Present Value Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Transmission O&M per mile Uprate existing 2.2 miles-12 inch HP minus Distribution O&M per mile (12 inch becomes transmission)and 2 for pipe that would go to N/A State Street Phase II Uprate miles of 4 inch HP transmission main ($1,085,641) $ (1,200,000) $ 4,208 $ 4,293 $ 4,378 $ 4,466 $ 4,555 $ 4,646 $ 4,739 Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Year 16 Year 17 Year 18 Year 19 Year 20 $ 4,834 $ 4,931 $ 5,029 $ 5,130 $ 5,233 $ 5,337 $ 5,444 $ 5,553 $ 5,664 $ 5,777 $ 5,893 $ 6,011 $ 6,131 3 Intermountain Gas Company Idaho Falls Lateral AOI Net Present Value 2026 Deficit Alternative N Alternative Description Details O&M Cost Used for NPV Net Present Value Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Wapello Compressor N/A Station Compressor Compressor O&M cost per j(314,039) ear ($34,783,485) $ (32,520,992) $ (257,621) $ (262,774) $ (268,029) $ (273,390) $ (278,857) $ (284,435) $ (290,123) Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Year 16 Year 17 Year 18 Year 19 Year 20 $ (295,926) $ (301,844) $ (307,881) $ $ (320,320) $ (326,726) $ (333,260) $ (339,926) $ (346,724) $ (353,659) $ (360,732) $ (367,946) $ (375,305) 2030 Deficit Alternative H lAlternative Description IDetalls JO&M Cost Used for NPV Net Present Value I Year 0 I Year 1 I Year 2 1 Year 3 1 Year 4 1 Year 5 1 Year 6 1 Year 7 Fort Hall Compressor 1 Station Compressor Compressor O&M cost per year 1 ($48,359,768) $ (46,732,645) $ (257,621) $ (262,774) $ (268,029) $ (273,390) $ (278,857) $ (284,435) $ (290,123) Year 8 Year 9 Year 30 Year 11 Year 12 Year 13 Year 14 Year 15 Year 16 Year 17 Year 18 Year 19 Year 20 $ (295,926) $ (301,844) $ (307,881) $ (314,039) $ (320,320) $ (326,726) $ (333,260) $ (339,926) $ (346,724) $ (353,659) $ (360,732) $ (367,946) $ (375,305) 2030 Deficit Alternative N Alternative Description Details O&M Cost Used for NPV Net Present Value Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Compressor Suction 8.5 miles of 16-inch 2 Pipeline Reinforcement Transmission Transmission O&M cost per year ($40,240,247) $ (42,000,000) $ (8,178) $ (8,341) $ (8,508) $ (8,678) $ (8,852) $ (9,029) $ (9,209) Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Year 16 Year 17 Year 18 Year 19 Year 20 $ (9,394) $ (9,581) $ 9,773 $ 9,968 $ 10,168 $ 10,371 $ 10,579 $ 10,790 $ 11,006 $ 11,226 $ 11,451 $ 11,680 $ 11,913 4 Intermountain Gas Company Transmission O&M Cost per Mile per Year From Accounting Records From FERC Form 2 From FERC Form 2 Sub Account Description 2022 2021 2020 3-Year Average Operation Expense: 28520 Communication System Expenses 24,308.33 $ 30,703.63 33,366.62 28560 Mains Expenses 1,793.54 1,805.21 2,088.74 Maintenance Expense: 28630 Maintenance of Mains 125,200.04 26,172.53 12,617.11 28631 Maintenance of Mains 142,328.11 28660 Maintenance of Communication Equip 139,601.91 131,969.39 139,345.50 Total $ 290,903.82 $ 190,650.76 $ 329,746.08 Total Miles of Transmission Line 284 279.49 279.5 O&M Cost per Mile $ 1,024.31 $ 682.14 $ 1,179.77 $ 962.07 5 Intermountain Gas Company Distribution Main O&M Cost per Mile per Year From FERC Form 2 From FERC Form From FERC Form 2 iub Accoun Description 2022 2021 2020 3-Year Average Distribution O&M Expenses $ 25,445,520 $ 24,742,508 $ 21,886,836 28920 Less: Maintenance of Services $ (3,084,202) $ (3,604,219) $ (2,669,868) 28930 Less: Maintenance of Meters and Hi $ (1,350,994) $ (988,180) $ (864,005) Total Distribution O&M Expenses $ 21,010,324 $ 20,150,109 $ 18,352,963 Total Miles of Distribution Line 7,155.00 6,970.00 6,560.63 O&M Cost per Mile $ 2,936.45 $ 2,890.98 $ 2,797.44 $ 2,874.96 6 Intermountain Gas Company Compressor Station Operations and Maintenance Estimate Jerome Description Frequency(Yrs) Unit Price Annualized Cost Notes Annual Service Overhaul 1 $15,000 $15,000 materials,labor and travel 15K Jerome 25K Shoshone Misc Repair 2 $2,500 $1,250 example:Bettis actuator failure in 2016/2017,starting system repair 2020, Every 8000 hr Maintenance 10 $60,000 $6,000 est cost and frequency Oil Change 2 $1,200 $600 est cost and frequency Emissions Test 3 $6,000 $2,000 3 year requirement Misc Maintenance 1 $5,000 $5,000 land,fence,paint,electricity*added 2900 budgeted amount electricity* Weekly Check(winter) 1 $8,960 $8,960 10perators for 4 hrs a week for 4 months Monthly Startup(Fall,winter,Spring) 1 $20,160 $20,160 2 Operators for 8 hrs a month for 9 months Monthly Check(non-winter) 1 $3,360 $3,360 1 Operator for 8 hrs a month for 3 months Peak Shaving Operators 1 $11,200 $11,200 2 Operators for 8 hrs a day for 5 days a year... Peak Shaving Operators STBY 1 $20,520 $20,520 1 Operators for 18 hours per week per CWE(2022-23 was 76 days)50/50 Jerome and SS Test Run-NG Fuel 1 $822 $822 6 hr/month for 9 months at 50 th/hr and$0.50/th(WACOG cost of gas 2023)*updated with budgeted amounts fy'21* Peak Shaving-NG Fuel 1 $1,827 $1,827 5 days at 24 hrs/day and 50 th/hr at$0.50/th(WACOG cost of gas 2023) Estimated Total Annual Costs: $96,700 Shoshone Description Frequency(Yrs) Unit Price Annualized Cost Notes Annual Service Overhaul 1 $25,000 $25,000 materials,labor and travel Misc Repair 2 $30,000 $5,000 example:Bettis actuator failure in 2016/2017,starting system repair 2020, Every 8000 hr Maintenance 10 $60,000 $6,000 est cost and frequency Oil Change 2 $6,000 $3,000 est cost and frequency Emissions Test 3 $6,000 $2,000 3 year requirement Misc Maintenance 1 $5,000 $5,000 land,fence,paint,electricity*added 3000 budgeted amount electricity* Weekly Check(winter) 1 $17,920 $17,920 1 Operators for 8 hrs a week for 4 months Monthly Startup(Fall,winter,Spring) 1 $20,160 $20,160 2 Operators for 8 hrs a month for 9 months Monthly Check(non-winter) 1 $3,360 $3,360 1 Operator for 8 hrs a month for 3 months Peak Shaving Operators 1 $33,600 $33,600 2 Operators for 8 hrs a day for 15 days a year... Peak Shaving Operators STBY 1 $20,520 $20,520 1 Operators for 18 hours per week per CAT(2022-23 was 76 days)50/50 Jerome and SS Test Run-NG Fuel 1 $2,960 $2,960 6 hr/month for 9 months at 180 th/hr and$0.50/th(WACOG cost of gas 2023)*updated with budgeted amounts fy'21* Peak Shaving-NG Fuel 1 $19,735 $19,735 15 days at 24 hrs/day and 180 th/hr at$0.50/th(WACOG cost of gas 2023) Estimated Total Annual Costs: $164,255 *Assumed Operator salary is$140/hr loaded Wapello Compressors(2 as of 2024) Description Frequency(Yrs) Unit Price Annualized Cost Notes Annual Service Overhaul 1 $40,000 $40,000 materials,labor and travel 20K each engine Misc Repair 2 $50,0D0 $25,000 example:Valve repairs,or computertuning,or safety device Every 8000 hr Maintenance 10 $60,0D0 $6,000 est cost and frequency Oil Change every 2,000 hours 5 $6,000 $1,200 est cost and frequency Emissions Test 3 $10,000 $3,333 3 year requirement unless extension is granted Misc Maintenance 1 $8,000 $8,000 land,fence,paint,electricity*added 3500 budgeted amount electricity* Weekly Check(winter) 1 $35,840 $35,840 2 Operators for 8 hrs a week for 4 months Monthly Startup(Fall,winter,Spring) 1 $20,160 $20,160 2 Operators for 8 hrs a month for 9 months Monthly Check(non-winter) 1 $3,360 $3,360 1 Operator for 8 hrs a month for 3 months Peak Shaving Operators 1 $31,360 $31,360 2 Operators for 8 hrs a day for 14 days a year...assuming the compressor will run every year Peak Shaving Operators STBY 1 $45,360 $45,360 1 Operators for 18 hours per week per peak shaving times of Dec-Feb Test Run-NG Fuel 1 $17,542 $17,542 6 hr/month for 9 months at 200 th/hr and$0.50/th(WACOG cost of gas 2023)*updated with budgeted amounts fy'21* Peak Shaving-NG Fuel 1 $20,466 $20,466 14 days at 24 hrs/day and 200 th/hr at$0.50/th(WACOG cost of gas 2023) Estimated Total Annual Costs: $257,621 *Assumed Operator salary is$140/hr loaded Idaho Estimated Total Annual Costs for 4 Compressors $518,576 7