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Agenda Item V.1_Wastewater Rate Study Report
REPORT Wastewater Rate Study County of Hawai`i Department of Environmental Management Wastewater Division August 2026 Prepared by: FG SOLUTIONS PO Box 48193 Los Angeles CA 90048-0193 www.fg-solutions.com PO Box 48193 Los Angeles, CA 90048-0193 REPORT Wastewater Rate Study Prepared for County of Hawai`i Department of Environmental Management Wastewater Division 108 Railroad Ave., Hilo, HI 96720 August 10, 2026 This report has been prepared for the use of the client for the specific purposes identified in the report. The conclusions, observations and recommendations contained herein attributed to FG Solutions, LLC constitute the opinions of FG Solutions, LLC. To the extent that statements, information and opinions provided by the client or others have been used in the preparation of this report, FG Solutions, LLC has relied upon the same to be accurate, and for which no assurances are intended and no representations or warranties are made. FG Solutions, LLC makes no certification and gives no assurances except as explicitly set forth in this report. © 2026 FG Solutions, LLC All rights reserved. ii County of HAWAII Wastewater Rate Study Report 08102026 A Table of Contents Table of Contents List of Tables List of Figures List of Abbreviations ................................................................................................................................... iv Executive Summary ..................................................................................................................................... 1 1. Background and Report Organization ..............................................................................................1-1 1.1 Introduction .............................................................................................................................1-1 1.2 Current Wastewater Service Charges ....................................................................................1-1 1.3 Administrative Order of Consent ............................................................................................1-2 1.4 Project Approach and Methodology .......................................................................................1-2 2. Revenue Requirement Analysis .......................................................................................................2-1 2.1 Introduction .............................................................................................................................2-1 2.2 Revenues .................................................................................................................................2-1 2.2.1 Key Assumptions ......................................................................................................2-1 2.2.2 Non-Rate Revenues..................................................................................................2-1 2.2.3 Rate Revenues under Current Rates ......................................................................2-1 2.2.4 Rate Revenues from Proposed Rate Increases......................................................2-2 2.3 Expenses .................................................................................................................................2-2 2.3.1 Key Assumptions ......................................................................................................2-2 2.3.2 O&M Expenses .........................................................................................................2-3 2.3.3 Equipment Replacement Fund ................................................................................2-4 2.3.4 Additional Facilities Repairs ....................................................................................2-4 2.3.5 Capital Improvements ..............................................................................................2-4 2.3.6 Debt ...........................................................................................................................2-4 2.4 Reserves ..................................................................................................................................2-5 2.5 Operating Statement ..............................................................................................................2-5 3. Rate Structure Development ............................................................................................................3-1 3.1 Cost-of-Service Analysis ..........................................................................................................3-1 3.2 Policy Considerations .............................................................................................................3-3 4. Proposed Wastewater Service Charges ...........................................................................................4-1 4.1 Current Wastewater Service Charges ....................................................................................4-1 4.2 Proposed Wastewater Service Charges ................................................................................4-1 4.3 Comparison with Other Utilities .............................................................................................4-2 5. Ongoing Considerations and Recommendations ............................................................................5-1 Appendix A: Revenue Requirement Analysis .............................................................................................. 1 Wastewater Rate Study – County of Hawai’i, Wastewater Division Table of Contents ES-iii County of HAWAII Wastewater Rate Study Report 08102026 A Appendix B: Cost-of-Service Analysis and Rate Design ............................................................................. 1 Appendix C: Rate Study Supporting Calculations ....................................................................................... 1 List of Tables and Figures Table ES-1. ........................................................................................ Current Wastewater Service Charges Table ES-2 .................................................................................... Proposed Wastewater Service Charges Table 1-1. ........................................................................................... Current Wastewater Service Charges Table 2-1. .................... Historical and Projected Revenues Under Existing Wastewater Service Charges Table 2-2. ............................................................................................................. Projected O&M Expenses Table 2-3. ............ Projected Budget Allocation for Emergency Repairs and Additional Facilities Repairs Table 2-4. ...................................................................... Projected Wastewater Fund Operating Statement Table 3-1. .............................................................. FY 26/27 Functionalized Rate Revenue Requirement Table 3-2. ........................................................................ FY 26/27 Allocated Rate Revenue Requirement Table 3-3. .............................................................................................. Calculation of Unit Costs of Service Table 4-1. ........................................................................................... Current Wastewater Service Charges Table 4-2. ...................................................................................... Proposed Wastewater Service Charges Table 4-3. .................................................................. Monthly Bill Comparison For Single-Unit Residences Figure 1-1. ............................................................................................................ Overview of Methodology Figure 4-1. .................................................. Single-Unit Residential Monthly Wastewater Bill Comparison Table of Contents Wastewater Rate Study – County of Hawai’i, Wastewater Division iv County of HAWAII Wastewater Rate Study Report 08102026 A List of Abbreviations AOC Administrative Order on Consent AWWA American Water Works Association BOD Biochemical Oxygen Demand COS Cost of Service COSA Cost-of-Service Analysis COH County of Hawaii EPA U.S. Environmental Protection Agency ERF Equipment Replacement Fund FG Solutions FG Solutions, LLC FTE Full-Time Equivalent FY Fiscal year (July 1–June 30) kgal thousand gallon(s) M1 AWWA Manual of Water Supply Practices M1 mgd Million gallons per day O&M Operations and maintenance SRF State Revolving Fund TSS Total suspended solids WAS Waste Activated Sludge WWTP Wastewater Treatment Plant ES-1 County of HAWAII Wastewater Rate Study Report 08102026 A Executive Summary The County of Hawai`i Wastewater Division (“Division”) provides services to approximately 14,800 customers throughout Hawai`i County. The Division is governed by the nine-member Hawai`i County Council. As part of its ongoing management of the wastewater system, the Division has recognized the need to evaluate expenditures, revenues, and wastewater rates to ensure that the Division can continue to provide safe and reliable service. The Division operates six wastewater treatment facilities: Hilo, Kona, Papaikou, Kulaimano, Kapehu, and Honokaa. Each of the six treatment facilities is served by a wastewater treatment plant (“WWTP”) and a wastewater collection system. In addition, there are two gang cesspool systems, one each at Naalehu and Pahala. The Division has an ongoing operation and maintenance program to ensure the continued provision of wastewater conveyance and treatment services. The Division is conducting a Wastewater Rate Study that is intended to: • Summarize the projected wastewater revenue requirements for the study period for fiscal years FY 26/27 through FY 30/31. • Show a proposed schedule of wastewater rates effective beginning 1/1/2027 through 1/1/2031 for the Division’s consideration. • Outline potentially changing conditions with financial implications and recommendations for ongoing monitoring of these items. Historical and budgeted financial and operational data were provided by the Division and used by FG Solutions to develop the projected revenue requirement for the study period. The revenue requirement analysis was an iterative process and draft versions were revised based on comments and input provided by Division staff. Next, the revenue requirement was compared with the revenues generated by the existing rates to generate additional revenues needed from rate increases. Key assumptions used in the Revenue Requirement analysis are summarized in Section 2. Additional assumptions are provided in the printout of the Revenue Requirement calculations that comprise Appendix A. There are two appendices to this report. Appendix A contains the Revenue Requirement. Appendix B is the wastewater system Cost-of-Service Analysis and Rate Design Calculations. Table ES-1 contains the current Wastewater Service Charges. Single-Unit Residential, Multi-Unit Residential and Gang Cesspools are flat rate, with no usage charge. Non-Residential customers pay a flat rate plus a usage charge. Note that there is one discharge fee for all Private Haulers. Table ES-1. Current Wastewater Service Charges Executive Summary Wastewater Rate Study – County of Hawai’i, Wastewater Division ES-2 County of HAWAII Wastewater Rate Study Report 08102026 A Table ES-2 contains the Proposed Wastewater Service Charges. The proposed rates begin on 1/1/2027, and are increased on January 1 beginning in 2028, ending in 2031. There are new customer classes, a new Hotels customer class and Private Haulers have been separated into three different rate classes. The Hotels customer class takes into consideration the strength of wastewater from hotels, which was measured by sampling. The Private Hauler customer class considers the varied strength of wastewater from each subclass. Table ES-2. Proposed Wastewater Service Charges Ongoing Considerations and Recommendations The Department should continue to monitor its financial status on an ongoing basis, and should continue to monitor the following: • Development activity in the Division’s service area. A 1.0 percent annual system growth rate is projected through FY 30/31. New connections will increase the size of the Division’s customer base and result in increased wastewater rate revenues. Deviations in the actual growth rate from the projections in this Rate Study will have financial impacts that the Division should monitor over time. • Inflation rates. The projected rates are based on a 2.5 percent annual inflation rate for most items, noting that personnel expenses are projected to increase at a 5.0 percent annual rate. Deviations in inflation rates from these values will have financial implications. • O&M costs after completion of AOC capital projects. The Division is currently constructing upgrades at the Hilo WWTP, and an upgrade of the Kealakehe WWTP is planned. When these projects are complete, the costs to operate and maintain them will change. The Division should monitor O&M costs as these projects come online. • Impact Fees. The County should consider adopting a wastewater Impact Fee. An Impact Fee is a one-time that is charged to new customers connecting to the wastewater system. This fee is how new customers pay for their fair share of existing wastewater infrastructure. Existing,Proposed Customer Class 1/1/2026 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 Units ResidentialSingle-Unit Residential, Monthly Base Rate Charge $52.00 $63.00 $76.00 $91.00 $108.00 $125.00 $/Unit Multi-Unit Residential, Monthly Base Rate Charge $52.00 $63.00 $76.00 $91.00 $108.00 $125.00 $/Unit Gang Cesspools, Monthly Base Rate Charge $25.00 $32.00 $38.00 $46.00 $54.00 $62.00 $/Unit Non-Residential Monthly Base Rate Charge per Unit $54.00 $79.00 $94.00 $113.00 $134.00 $155.00 $/Unit Monthly Usage Charge per 1,000 Gallons 0 - 8 kgal (Included in Monthly Base Rate Charge)N/A N/A N/A N/A N/A N/A $/kgal8 - 15 kgal $7.50 $7.50 $9.00 $10.80 $12.75 $14.80 $/kgal 15 - 30 kgal $9.00 $9.00 $10.80 $12.95 $15.30 $17.75 $/kgal >30 kgal $9.50 $9.50 $11.40 $13.70 $16.15 $18.75 $/kgal Hotels Monthly Base Rate Charge $54.00 $96.00 $115.00 $138.00 $163.00 $189.00 $/Unit Monthly Usage Charge per 1,000 Gallons 0 - 8 kgal (Included in Monthly Base Rate Charge)N/A N/A N/A N/A N/A N/A $/kgal 8 - 15 kgal $7.50 $8.85 $10.60 $12.75 $15.05 $17.45 $/kgal 15 - 30 kgal $9.00 $10.35 $12.40 $14.90 $17.60 $20.40 $/kgal >30 kgal $9.50 $10.85 $13.00 $15.60 $18.45 $21.40 $/kgal Private Haulers, $ per 500 Gallons Septage and Cesspool $64.00 $100.00 $140.00 $180.00 $217.00 $252.00 $/500 gal Portable Toilets $64.00 $84.00 $104.00 $127.00 $150.00 $174.00 $/500 gal WWTP $64.00 $95.00 $125.00 $155.00 $173.00 $201.00 $/500 gal 1-1 County of HAWAII Wastewater Rate Study Report 08102026 A Section 1 Background and Report Organization 1.1 Introduction The County of Hawai`i Wastewater Division (“Division”) provides services to approximately 14,800 customers throughout Hawai`i County. The Division is governed by the nine-member Hawai`i County Council. As part of its ongoing management of the wastewater system, the Division has recognized the need to evaluate expenditures, revenues, and wastewater rates to ensure that the Division can continue to provide safe and reliable service. The Division operates six wastewater treatment facilities: Hilo, Kona, Papaikou, Kulaimano, Kapehu, and Honokaa. Each of the six treatment facilities is served by a wastewater treatment plant (“WWTP”) and a wastewater collection system. In addition, there are two gang cesspool systems, one each at Naalehu and Pahala. The Division has an ongoing operation and maintenance program to ensure the continued provision of wastewater conveyance and treatment services. The Division is conducting a Wastewater Rate Study that is intended to: • Summarize the projected wastewater revenue requirements for the study period for fiscal years FY 26/27 through FY 30/31. • Show a proposed schedule of wastewater rates effective beginning 1/1/2027 through 1/1/2031 for the Division’s consideration. • Outline potentially changing conditions with financial implications and recommendations for ongoing monitoring of these items. Historical and budgeted financial and operational data were provided by the Division and used by FG Solutions to develop the projected revenue requirement for the study period. The revenue requirement analysis was an iterative process and draft versions were revised based on comments and input provided by Division staff. Next, the revenue requirement was compared with the revenues generated by the existing rates to generate additional revenues needed from rate increases. Key assumptions used in the Revenue Requirement analysis are summarized in Section 2. Additional assumptions are provided in the printout of the Revenue Requirement calculations that comprise Appendix A. Figure 1.1 shows the overall approach to completing the scope of services. There are two appendices to this report. Appendix A contains the Revenue Requirement Analysis. Appendix B is the wastewater system Cost-of-Service Analysis and Rate Design Calculations. Appendix C is supplemental calculations that support the Rate Study. 1.2 Current Wastewater Service Charges The current Wastewater Service Charge schedule is shown below in Table 1-1. Rates shown are effective as of 1/1/2026. All customers pay a Monthly Base Rate Charge. Single-Unit Residential and Mult-Unit Residential customers pay the Monthly Base Rate Charge. For Non-Residential customers, the Monthly Base Rate Charge includes the first 8,000 gallons per month of water use. Above 8 kgal, Non-Residential customers pay a Usage Charge that increases with use. Private Haulers pay a Discharge Fee per 500 gallons. This fee is the same for all types of waste brought in by Private Haulers. Section 1 Wastewater Rate Study – County of Hawai’i, Wastewater Division 1-2 County of HAWAII Wastewater Rate Study Report 08102026 A Table 1-1. Current Wastewater Service Charges Notes: (1) County of Hawai`i Ordinance No. 1921, adopted February 20, 2019. Rates shown have been effective since 4/1/2023. (2) The first 8,000 gallons per month is included in the Monthly Base Rate Charge. Kgal = thousand gallons. 1.3 Administrative Order of Consent The County is under an Administrative Order of Consent (AOC) for Clean Water Act violations in its wastewater system. Currently, wastewater rates do not generate enough revenue to pay for debt service for capital projects. Wastewater rates, even with the proposed increases described in this report, will not be able to pay for projects related to the AOC. This rate study does not incorporate any of the AOC capital expenses in the rate structure. Because wastewater rates are not paying for any of the AOC capital projects, the AOC is not discussed in any detail in this report. It is mentioned in brief in later sections. 1.4 Project Approach and Methodology Figure 1.1 shows the overall approach to completing the scope of services. There are two appendices to this report. Appendix A contains the Revenue Requirement. Appendix B is the wastewater system Cost-of-Service Analysis and Rate Design Calculations. Wastewater Rate Study – County of Hawai’i, Wastewater Division Section 1 1-3 County of HAWAII Wastewater Rate Study Report 08102026 A Figure 1.1. Overview of Methodology Data and Policies Financial CustomerBilling Capital Improvement Plan Fiscal Policy Level of Service Revenue Requirement Cost of Service Analysis Rate Design Percentage of System-Wide Increase OK? Rate Schedule OK to present to Council? Environmental Management Commission / Council Meetings Council Approves Rate Schedule? Adoption and Implementation NO YES YES NO YES NO Wastewater Rate Study – County of Hawai’i, Wastewater Division Section 2 2-8 County of HAWAII Wastewater Rate Study Report 08102026 A Section 2 Revenue Requirement Analysis 2.1 Introduction To provide for the continued operation of a utility on a sound financial basis, revenues must be sufficient to meet the cash requirements for operation and maintenance (O&M) expense, debt service requirements, debt service coverage requirements, reserves, and cash-funded capital expenditures not financed with debt. The sum of these cost components for a given year is referred to as a utility’s Revenue Requirement. Historical and budgeted financial and operational data were provided by the Division and used by FG Solutions to develop the projected revenue requirement for the study period. The revenue requirement analysis was an iterative process and draft versions were revised based on comments and input provided by Division staff. Next, the revenue requirement was compared with the revenues generated by the existing rates to generate additional revenues needed from rate increases. The reserve requirement described below is met in the later years of the projection period as the proposed rates were developed to generate these reserve levels over time. Revenue projections are a critical part of the revenue requirement analysis. The three aspects of revenue projections described in the sections below are non-rate revenues, rate revenues under the current rate schedule, and rate revenues from proposed rate increases. Key assumptions used in the Revenue Requirement analysis are listed below. Additional assumptions are provided in the printout of the Revenue Requirement calculations that comprise Appendix A. 2.2 Revenues 2.2.1 Key Assumptions Revenue projections are a critical part of the revenue requirement analysis. The three aspects of revenue projections described in the sections below are non-rate revenues, rate revenues under the current rate schedule, and rate revenues from proposed rate increases. One of the key assumptions for this Rate Study is that wastewater revenues under existing rates in FY 26/27 thru FY 30/31 are based on actual revenues from FY 24/25. 2.2.2 Non-Rate Revenues The key sources of wastewater revenues other than rate revenues are the following: • General Fund Transfer. It has been a practice for the General Fund to transfer money to the Wastewater Fund on an annual basis. These funds are used to pay a portion of O&M expenses and replacement expenses. Recent transfers have ranged from $2 M to $6 M per year. • The Rate Study phases out General Fund Transfers by FY 30/31. • It is estimated that $322,000 per year will be reimbursed to the Utility for the Kaloko WWTP from FY 26/27 through FY 30/31. 2.2.3 Rate Revenues under Current Rates Rates that are currently effective are shown in Table 2.1 Historical and Projected Revenues. These rates are used to project the revenues found in the Division’s budget documents. Table 2.1 shows the Historical and Projected Revenues under existing rates. Section 1 Wastewater Rate Study – County of Hawai’i, Wastewater Division 2-2 County of HAWAII Wastewater Rate Study Report 08102026 A Table 2-1. Historical and Projected Revenues Under Existing Wastewater Service Charges Notes: (1) Projections are based on actual FY 23/24 revenues escalated for 1% system growth every year. (2) The COH is reimbursed by third parties for operating the Kaloko WWTP. Projected reimbursement is expected to remain at FY 23/24 values through FY 30/31. The source of projected revenues in this Rate Study are from the Division’s actual FY 24/25 revenues, adjusted for a projected 1% annual system growth rate. The Division’s actual growth rate over the past five years has been approximately 1% per year. 2.2.4 Rate Revenues from Proposed Rate Increases Rate revenues resulting from proposed rate increases are shown later in this report. 2.3 Expenses 2.3.1 Key Assumptions Operations and Maintenance (“O&M”) expenses through FY 26/27 are based on the Division’s FY 26/27 and FY 27/28 budget and budget estimates. In some cases, the Division modified the Division’s budget and budget estimates for the purposes of the wastewater Rate Study. For FY 26/27 the FY 26/27 budget was used. For FY 27/28, the FY 27/28 budget was used, except for equipment, where the FY 26/27 budget was used. For FY 26/27 projected O&M expenses, inflation is projected at 2.5% per year, unless otherwise noted. Salaries and wages are projected to increase at 5.0% per year. For the purposes of this rate study, FG Solutions and the Division identified any significant deviations in O&M expenses compared with the Division’s FY 26/27 budget. The following deviations from the Division’s budget documents include: a) Employee health benefits, retirement benefits, and Federal Insurance Contributions Act (FICA) employer share collectively are projected to be 43% of salary expense. This is the percentage used in the County’s FY 25/26 budget. b) COH intends to hire new employees needed to operate new facilities in Naalehu and Pahala. An additional 3 full-time equivalents (FTEs) are planned in FY 28/29. The Division uses an O&M “Percentage Underspend Factor” to recognize that the Division historically spends less than its budget. For personnel expenses, a 20% underspend factor was used in FY 26/27 and a 15% underspend Projected FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Wastewater Service Charges under Existing Rates (1) Hilo $7,313,248 $7,386,381 $7,460,245 $7,534,847 $7,610,195 $7,686,297 Honokaa 177,783 179,561 181,357 183,170 185,002 186,852 Kapehu 17,831 18,009 18,189 18,371 18,555 18,740 Kona 7,282,028 7,354,848 7,428,397 7,502,681 7,577,707 7,653,484 Kulaimano 382,223 386,046 389,906 393,805 397,743 401,721 Naalehu 42,654 43,081 43,512 43,947 44,386 44,830 Pahala 30,636 30,943 31,252 31,565 31,880 32,199 Papaikou 296,515 299,480 302,475 305,499 308,554 311,640 Private Haulers 750,091 757,592 765,168 772,819 780,547 788,353 Subtotal Wastewater Service Charges 16,293,010 16,455,940 16,620,499 16,786,704 16,954,571 17,124,117 Other Revenues Kaloko WWTP Reimbursement (2)322,501 322,501 322,501 322,501 322,501 322,501 Total Sewer Revenues $16,615,510 $16,778,441 $16,943,000 $17,109,205 $17,277,072 $17,446,618 Wastewater Rate Study – County of Hawai’i, Wastewater Division Section 1 2-3 County of HAWAII Wastewater Rate Study Report 08102026 A factor was used in FY 27/28 through FY 34/35. An additional underspend factor of 7% was applied to all other O&M expenses from FY 26/27 through FY 30/31. 2.3.2 O&M Expenses Table 2.2 Projected O&M Expenses shows the basis for projection of O&M expenses for the ten-year Study period. Additional details are included in the Appendix. A summary of O&M expenses by Department section is shown in Appendix A Table 5. Projected O&M expenditures are primarily based on the Division’s FY 26/27 and FY 27/28 budgets, and some specific adjustments to the Division’s budget were made based on other known or anticipated conditions. Table 2-2. Projected O&M Expenses Notes: (1) Projections are based on draft FY 26/27 and FY 27/28 budgets, with a 5% annual inflation increases starting in FY 28/29. The budget is based on the cost of authorized staffing positions. Actual historical expenses are less than budget due to unfilled positions. See projected Underspend calculation in this table. (2) New positions not included in the FY 26/27 and FY 27/28 budgets include 3 FTEs serving Naalehu and Pahala beginning in FY 28/29. The projected cost per FTE is $125K/year per FTE through FY 28/29. (3) Projections are based on draft FY 26/27 and FY 27/28 budget, with a 2.5% annual inflation increases starting in FY 28/29. (4) Projected expenses are also escalated by the projected 1.0% annual rate of system growth. Projected FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes Department 631: Wastewater Staffing, Current Staffing Plan $7,285,743 $8,513,787 $8,939,476 $9,386,450 $9,855,773 1 Staffing, New Positions 0 0 375,000 393,750 413,438 2 Wastewater OCE (Other Current Expense)3 Equip Repairs/Maintenance 334,100 334,100 342,453 351,014 359,789 Repairs to Facilities 920,000 920,000 943,000 966,575 990,739 Rental/Lease of Equipment 585,491 695,556 712,945 730,769 749,038 Water, Gas and Sewer 178,530 178,530 182,993 187,568 192,257 Electricity 3,660,168 3,660,168 3,789,189 3,922,758 4,061,035 4 Misc. Contract Services 1,039,560 1,508,560 1,546,274 1,584,931 1,624,554 Refuse Disposal 830,000 830,000 859,258 889,546 920,903 4, 5 Cleaning/Sanitation Supplies 938,500 938,500 971,582 1,005,830 1,041,286 4, 6 M.V./Hvy Eqpt Parts/Supp 542,200 542,200 555,755 569,649 583,890 Misc. Materials & Supp 373,400 373,400 382,735 392,303 402,111 Building Rent 135,000 135,000 138,375 141,834 145,380 EM Admin Fees 346,411 352,625 382,191 412,497 443,560 7 Other Wastewater OCE 1,444,059 1,449,209 1,464,688 1,480,555 1,496,818 Equipment 3,665,600 3,757,240 3,851,171 3,947,450 4,046,137 Subtotal, Department 631 $22,278,762 $24,188,875 $25,437,085 $26,363,480 $27,326,708 Dept 901: Pensions & Contributions $3,085,300 $3,660,928 $4,005,225 $4,205,486 $4,415,760 8 Dept 911: Workers Comp Charges $275,000 $365,000 $374,125 $383,478 $393,065 3 Dept 913: Provision for Training $27,683 $28,375 $29,084 $29,812 $30,557 3 Less Underspend Personnel Underspend ($2,074,209) ($1,826,207) ($1,997,955) ($2,097,853) ($2,202,746)9 Other O&M Underspend ($1,070,699) ($1,124,792) ($1,156,807) ($1,189,760) ($1,223,678)9 Subtotal, Underspend ($3,144,908) ($2,951,000) ($3,154,762) ($3,287,613) ($3,426,424) Total O&M $22,521,837 $25,292,179 $26,690,757 $27,694,643 $28,739,666 Section 1 Wastewater Rate Study – County of Hawai’i, Wastewater Division 2-4 County of HAWAII Wastewater Rate Study Report 08102026 A (5) These expenses are primarily disposal of solids generated at the WWTPs. (6) The majority of these expenses are for WWTP chemicals. (7) These are expenses charged by the County's General Fund for administrative services. (8) Projected pension and contributions expense is 43% of salaries and wages expense, calculated from the County's draft FY 26/27 budget. (9) Underspend acknowledges that the Wastewater Division actual spending is typically less than its budget. For the purposes of this Rate Study, 15% underspend for personnel expenses is applied and a 7% underspend for all other O&M expenses is applied. The actual underspend varies from year to year and in recent years has exceeded 10%. 2.3.3 Equipment Replacement Fund The Division has an Equipment Replacement Fund (ERF), which pays for replacement projects. The source of funds for ERF projects is wastewater rates. The proposed transfer to the Equipment Replacement Fund is $1 million per year is consistent with recent Division practice. Table 2-3, Projected Budget Allocation for Emergency Repairs and Additional Facilities Repairs, shows the projected ERF transfers through FY 30/31. Table 2-3. Projected Budget Allocation for Emergency Repairs and Additional Facilities Repairs Notes: (1) An annual $1M transfer to the Division's Emergency Replacement Fund is projected, consistent with the County's recent practice. (2) Additional Facilities Repairs are required by the County's AOC. A phase-in of these repairs up to $5M per year by FY 30/31 is projected. County staff also are planning approximately $3.4M in FY 26/27 which will be funded from existing Wastewater Fund reserves. 2.3.4 Additional Facilities Repairs The Division is accelerating the implementation of Additional Facilities Repairs required by the AOC. The projected spending on Additional Facilities Repairs is gradually increased to $5 million per year by FY 30/31. The County intends on spending approximately $3.4 million in FY 26/27, to be funded with existing wastewater fund balance. Table 2-3 shows the projected Additional Facilities Repairs expenses through FY 30/31. 2.3.5 Capital Improvements Capital Improvements, such as system expansions, major rehabilitation projects, and treatment plant upgrades, are currently funded by the County’s General Fund. The County’s General Fund is also currently funding capital costs related to AOC compliance. Wastewater rates, even with the proposed rate increases, are not sufficient to fund capital improvements. As a result, capital improvement funding is not addressed in this Rate Study. A requirement of the AOC is to complete a Financial Plan for Critical Capital Improvement Projects. The AOC requires than an Interim Financial Plan be completed by June 30, 2027. This financial plan is required to contain “a detailed descriptive plan for raising sufficient revenue to meet the projected costs”. 2.3.6 Debt At this time, wastewater rates do not support debt service. Debt service payments on existing loans are made by Hawaii County’s General Fund. This has been a long-standing practice of the Division. Projected FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Emergency Repairs (1)$1,000,000 $1,000,000 $1,000,000 $1,000,000 $1,000,000 Additional Facilities Repairs (2)$3,385,599 $2,000,000 $3,000,000 $4,000,000 $5,000,000 Wastewater Rate Study – County of Hawai’i, Wastewater Division Section 1 2-5 County of HAWAII Wastewater Rate Study Report 08102026 A 2.4 Reserves As shown in more detail in Section 2.5 (Operating Statement) and in Appendix A, the Division maintains reserves in the Wastewater Fund and in the Equipment Replacement Fund. As of 6/30/2025, the wastewater fund balance is approximately $16.4 million. A portion of the wastewater fund balance will be used to pay for Additional Facilities Repairs and a portion of the Division’s equipment expenses in FY 26/27. At the end of FY 30/31 the projected wastewater fund balance is approximately $13.6 million. The Division does not have a formal policy regarding a minimum fund balance. At the end of FY 30/31 the projected wastewater fund balance of $13.6 million is approximately equivalent to 173 days of O&M and replacement expenses. Showing fund balance as days of expenses is a common metric to assess the amount of a fund balance, particularly by bond rating agencies. 173 days of O&M is of reasonable value, particularly given that the General Fund is currently responsible for wastewater debt service. As of 6/30/2025, the reserve balance in the Equipment Replacement Fund was $4.7 million. This reserve is available for use if equipment replacement needs exceed the $1 million transfer in a given year. The County does not have a formal policy regarding a minimum balance in the Equipment Replacement Fund. 2.5 Operating Statement Table 2.4 Projected Wastewater Fund Operating Statement shows the beginning and ending year fund balance revenues and expenses. Revenues from projected rate increases are shown separately in Table 2.4. The projected rate increases are discussed in further detail in Sections 3 and 4. Table 2-4. Projected Wastewater Fund Operating Statement Notes: (1) See Appendix A Table 8, Projected Operating Statement, for more details. (2) The projected General Fund Transfer is based on the budgeted O&M expenses shown in Table 2-2, Projected O&M Expenses. The actual General Fund Transfer will depend on actual O&M expenses. Projected FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Beginning Year Fund Balance $16,359,872 $11,212,678 $11,212,678 $11,212,678 $11,212,678 Revenues (1) Wastewater Service Charges Under Existing Rates $16,455,940 $16,620,499 $16,786,704 $16,954,571 $17,124,117 From Proposed Rate Increases 1,122,933 4,399,083 8,879,353 14,062,742 19,678,766 Kaloko WWTP Reimbursement 322,501 322,501 322,501 322,501 322,501 General Fund Transfer (2)3,858,869 6,950,096 4,702,199 1,354,829 0 Total Revenues $21,760,242 $28,292,179 $30,690,757 $32,694,643 $37,125,384 Expenses (1) O&M (2)$22,521,837 $25,292,179 $26,690,757 $27,694,643 $28,739,666 Transfer to Equipment Repl Fund 1,000,000 1,000,000 1,000,000 1,000,000 1,000,000 Additional Facilities Repairs (3)3,385,599 2,000,000 3,000,000 4,000,000 5,000,000 Total Expenses $26,907,436 $28,292,179 $30,690,757 $32,694,643 $34,739,666 Revenues Minus Expenses (4)($5,147,194) $0 $0 $0 $2,385,718 Ending Year Fund Balance $11,212,678 $11,212,678 $11,212,678 $11,212,678 $13,598,396 Section 1 Wastewater Rate Study – County of Hawai’i, Wastewater Division 2-6 County of HAWAII Wastewater Rate Study Report 08102026 A (3) Additional Facilities Repairs are required by the AOC to address ongoing collection system needs. In 2024, COH staff provided direction to gradually increase facilities repairs to $5M per year over a five-year period. As described in Note 4 below, COH is budgeting additional funds for these repairs in FY 26/27. (4) In FY 26/27, revenues are projected to exceed expenses. This was an intentional policy decision of the County, with the intention of using fund balance to pay expenses including the Additional Facilities Repairs. In the past, the Wastewater Division’s revenues have not been sufficient to cover wastewater O&M and replacement costs. To account for this difference, an annual General Fund transfer is made to provide the remaining required revenue. The amount of the General Fund transfer is determined as the Wastewater Division budget is prepared on an annual basis. The projected General Fund transfers shown in this report are for illustrative purposes. As future budgets are prepared, County staff will develop updated General Fund transfers. Other notes regarding General Fund Transfers: 1. The FY 26/27 General Fund transfer was obtained from the Division’s FY 26/27 Budget. 2. In FY 27/28 and subsequent years, the General Fund transfer is calculated based on the Wastewater Division budget and the underspend assumptions. The General Fund transfer in this report does not incorporate any further use of the wastewater fund balance other than what has been incorporated into the FY 26/27 budget. With the proposed rate increases, the General Fund transfer will be eliminated by the end of FY 30/31. In FY 26/27, expenses are projected to exceed revenues. This was an intentional policy decision of the County, with the intention of using fund balance to pay expenses including the Additional Facilities Repairs. 3-1 County of HAWAII Wastewater Rate Study Report 08102026 A Section 3 Rate Structure Development This section outlines the proposed wastewater rate structure. The rate structure is developed using a Cost-of-Service Analysis (COSA), completed consistently with industry standards. This COSA used methodology from 1) the American Water Works Association’s M1 Manual, Principles of Water Rates, Fees, and Charges (7th Edition), and 2) the Water Environment Federation’s Manual of Practice No. 27, Financing and Charges for Wastewater Systems. 3.1 Cost-of-Service Analysis A Cost-of-Service Analysis is completed in three steps: functionalization, allocation, and distribution. These steps and a summary of the results are shown below. Refer to Appendix B for detailed calculations. In the functionalization step, wastewater system expenses are grouped according to the functions of a wastewater system. Wastewater functions include treatment, collection (including pump stations), customer, and administration. Additional expenses are directly assigned to certain customer classes including Private Haulers and Gang Cesspools. Pretreatment expenses are separately isolated and are assigned to non-residential customers later in the COSA. Table 3-1, FY 26/27 Functionalized Rate Revenue Requirement, shows the functionalization of the Division’s rate revenue requirement for FY 26/27. Some of the key aspects of the functionalization calculations are: • Labor costs and employee benefits were functionalized based on a review, per employee, of their job descriptions. • Electricity costs were functionalized based on a review of electricity bills. • Most of the equipment and supplies costs were functionalized eighty percent to the treatment plants and twenty percent to the collection system, based on a review of the specific equipment and supply expenses. Table 3-1. FY 26/27 Functionalized Rate Revenue Requirement Functional Category (1)FY 26/27 $ Treatment $12,009,377 Collection 6,627,238 Customer 143,446 Direct Assign - Private Haulers (2)221,329 Direct Assign - Gang Cesspools (2)6,371 Direct Assign - Pretreatment 435,472 Administration 3,078,605 Total $22,521,837 Transfer to Equipment Replacement Fund (3)$1,000,000 Additional Facilities Repairs (3)3,385,599 Less Reimbursement for Kaloko WWTP (3)(322,501) Less Transfer from General Fund (3)(3,884,742) Change in Fund Balance (3)(5,147,194) Rate Revenue Requirement $17,553,000 Section 3 Wastewater Rate Study – County of Hawai’i, Wastewater Division 3-4 County of HAWAII Wastewater Rate Study Report 08102026 A Notes: (1) See Appendix B, Table COS-1 for more details. (2) Represents costs that are recovered in their entirety from the respective customer classes. (3) These items are not part of the functionalization process and are addressed in the Cost-of-Service Analysis Allocation step shown in Table 3-2. The next step in a Cost-of-Service Analysis is allocation, where functionalized expenses are allocated to wastewater characteristics of flow, biochemical oxygen demand (BOD), total suspended solids (TSS), and customer. Some of the key aspects of the allocation calculations are: • Treatment expenses are allocated one-third to flow, one-third to BOD, and one-third to TSS, • Collection expenses are allocated 90 percent to flow and 10 percent on a per-customer basis. • Customer expenses are allocated on a per customer basis. • Costs assigned directly to private haulers, gang cesspools, and pretreatment are carried through the allocation step to the rate design calculations. • Administrative expenses are allocated based on a weighted average of all other expenses. Table 3-2 shows the results of the allocation step. Detailed calculations are contained in Appendix B. Table 3-2. FY 26/27 Allocated Rate Revenue Requirement Notes: (1) See Appendix B, Table COS-2 for more detail. (2) Represents costs that are recovered in their entirety from the respective customer classes. (3) Represents costs that are recovered entirely from the non-residential customer class. The final step in a COSA is distribution, where the Rate Revenue Requirement is distributed to each customer class. Table 3-3 shows a portion of the distribution step, the calculation of unit costs of service. The first two lines of Table 3-3 shows the Rate Revenue Requirement for a twelve-month period where the Division would receive revenues from the 1/1/2027 rate increase. Table 3-3 shows unit cost calculations, where, for example, the flow component of the Rate Revenue Requirement is divided by the projected amount of wastewater flow from customers. Similarly, unit cost calculations for BOD and TSS are completed to generate the cost to treat a pound of BOD and a pound of TSS. The unit cost calculations are adjusted to recognize that customers on gang cesspools do not use the Division’s treatment plants, and private haulers do not use the Division’s collection system. These adjusted unit cost calculations are used in to develop the proposed wastewater service charges shown in Section 3.2. Cost Component (1)FY 26/27 $ Flow $10,388,880 BOD 3,033,456 TSS 3,033,456 Customer 601,995 Direct Assign - Private Haulers (2)165,274 Direct Assign - Gang Cesspools (2)4,757 Direct Assign - Pretreatment (3)325,182 Rate Revenue Requirement $17,553,000 Wastewater Rate Study – County of Hawai’i, Wastewater Division Section 1 3-3 County of HAWAII Wastewater Rate Study Report 08102026 A Table 3-3. Calculation of Unit Costs of Service Notes: (1) See Table 3-2, FY 26/27 Allocated Rate Revenue Requirement for more detail. (2) This row represents the 1/12 of the projected annual flow, BOD, and TSS discharged into the sewer system or brought by private haulers to a County Wastewater Treatment Plant. See Appendix A Tables 3a, 3b, and 3c for more detail. (3) The number of customers in this row is the projected number of customers receiving wastewater bills from the County. (4) Equals the rate revenue requirement, per month, divided by the units of service. (5) Gang cesspools do not use the County's wastewater treatment plants. They are not charged for the cost to treat wastewater at the wastewater treatment plants. (6) Private haulers do not use the County's wastewater collection system. (7) The unit cost-of-service for all other customers that use both the collection system and the wastewater treatment plant is recalculated after considering the adjustments made for gang cesspools and private haulers. 3.2 Policy Considerations The COSA described in Section 3.1 was used to develop the proposed wastewater rates. Additionally, Division identified policy considerations which were incorporated into the rate design. These policy considerations are included: 1. Creation of a new Hotels customer class. This customer class was created to provide greater equity in non- residential rates, recognizing that hotels typically discharge stronger wastewater than other non-residential customers. 2. The Non-residential Usage Charge in the proposed 1/1/2027 rate increase is unchanged. The proposed 1/1/2027 non-residential Usage Charge is maintained at the current level. Additional revenues collected from maintaining the current non-residential Usage Charge are used to partially offset proposed residential rate increases. 3. During the adoption of the previous set of rate increases in 2018, the County adopted a tiered Usage Charge structure for non-residential customers. This policy is retained in the proposed rates, and both non- residential and hotel rates have a tiered Usage Charge structure. 4. Establishing a new customer class for private haulers of portable toilet waste. The waste from portable toilets is typically not as strong as that from cesspools and septic tanks. A new Private Hauler - Portable Toilets customer class was created to recognize these customers and provide more equitable rates. 5. Phased-in rate increases for private haulers of septage waste, cesspool waste and portable toilets. As part of the concurrent wastewater planning efforts, the Division sampled wastewater at the Hilo septage receiving station. Based on this recent sampling, the cost-of-service analysis showed that the current rates for hauled waste are lower than the cost of service. A significant rate increase for septage and cesspool waste is needed for the Division to recover the costs of treating septage and cesspool waste. The rate Direct -Direct Private Gang Direct - Flow BOD TSS Customer Haulers Cesspools Pre-Treatment Total Rate Revenue Requirement (1) Full Year $10,388,880 $3,033,456 $3,033,456 $601,995 $165,274 $4,757 $325,182 $17,553,000 Per Month, After 11/1/26 Rate Increase $973,957 $284,386 $284,386 $56,437 $15,494 $446 $30,486 $1,645,593 Projected FY 25/26 Units of Service, per Month Amount (2) (3)147,123 253,742 248,831 6,162Unitskgallbslbscustomers Unit Cost-of-Service, $/unit $/kgal $/lb BOD $/lb TSS $/customer/mo. Unadjusted (4)6.62 1.12 1.14 9.16Adjusted Gang Cesspools (5)3.33 0.00 0.00 9.16Private Haulers (6)3.33 1.13 1.15 9.16 All Other Customers (7)6.67 1.13 1.15 9.16 Section 3 Wastewater Rate Study – County of Hawai’i, Wastewater Division 3-4 County of HAWAII Wastewater Rate Study Report 08102026 A increases are phased in over a three-year period to minimize sudden financial impacts to private haulers and their customers. 6. Creation of a new Private Haulers – WWTP customer class. The Division accepts hauled waste activated sludge (WAS) at Hilo and Kealakehe from non-county wastewater treatment plants. The proposed rate for these customers equals the calculated cost-of-service. The Wastewater Service Charge for residential customers is a flat Monthly Base Rate Charge. Non-residential and the new Hotel customer class also pay a Monthly Base Rate Charge and a Usage Charge that depends on metered water consumption. Private Haulers pay only a Discharge Fee per 500 gallons. Proposed Wastewater Service Charges through FY 30/31 are discussed in Section 4, Proposed Wastewater Service Charges 4-1 County of HAWAII Wastewater Rate Study Report 08102026 A Section 4 Proposed Wastewater Service Charges 4.1 Current Wastewater Service Charges Table 4-1 shows current wastewater service charges. Single-unit residential and multi-unit residential customers pay a flat Monthly Base Rate Charge of $52.00 for each unit. As described in Section 3, non-residential customers pay a Monthly Base Rate of $54 and a Usage Charge that depends on metered water consumption. For non-residential customers, the Monthly Base Rate includes the first 8,000 gallons of water consumption per month. Table 4-1: Existing Wastewater Service Charges Notes: (1) County of Hawai`i Ordinance No. 1921, adopted February 20, 2019. Rates shown have been effective since 4/1/2023. (2) The first 8,000 gallons per month is included in the Monthly Base Rate Charge. kgal = thousand gallons. 4.2 Proposed Wastewater Service Charges Table 4-2 Proposed Wastewater Service Charges shows the proposed wastewater service charges through FY 30/31. A series of five rate increases is proposed, with the first increase would be effective on 1/1/2027 and subsequent rate increases effective each January 1 starting in 2028. Monthly Base Usage Rate Charge Charge per Discharge Customer Class Per Unit (1) 1,000 Gallons Fee Units Single-Unit Residential $52.00 Per Unit Multi-Unit Residential $52.00 Per Unit Gang Cesspools $25.00 Per Unit Non-Residential $54.00 Per Unit 0 - 8 kgal/month (2)N/A Per kgal/month 8 - 15 kgal/month $7.50 Per kgal/month 15 - 30 kgal/month $9.00 Per kgal/month >30 kgal/month $9.50 Per kgal/month Private Haulers $64.00 Per 500 gallons Section 4 Wastewater Rate Study – County of Hawai’i, Wastewater Division 4-2 County of HAWAII Wastewater Rate Study Report 08102026 A Table 4-2. Proposed Wastewater Service Charges 4.3 Comparison with Other Utilities Figure 4-1 and Table 4-3 compares a monthly single-unit residential wastewater bill with Maui County, County of Kaua`i, the City and County of Honolulu, and the West Hawai`i Sewer Company. The comparison shows the existing rates, and future rate increases that have already been adopted. Of the other utilities, the current lowest monthly wastewater bill for a single-unit residence is Kauai’s, at $82.00. Kaua`i’s has adopted rate increases effective on July 1 of each year through 2028. On 7/1/2028, the wastewater bill on Kaua`i will be $101 per month for a single-unit residence. Maui County and the City and County of Honolulu wastewater rates are based on billed water consumption. The data in Figure 4-1 and Table 4-3 are based on monthly water use of 9 kgal per month. Existing,Proposed Customer Class 1/1/2026 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 Units ResidentialSingle-Unit Residential, Monthly Base Rate Charge $52.00 $63.00 $76.00 $91.00 $108.00 $125.00 $/Unit Multi-Unit Residential, Monthly Base Rate Charge $52.00 $63.00 $76.00 $91.00 $108.00 $125.00 $/Unit Gang Cesspools, Monthly Base Rate Charge $25.00 $32.00 $38.00 $46.00 $54.00 $62.00 $/Unit Non-Residential Monthly Base Rate Charge per Unit $54.00 $79.00 $94.00 $113.00 $134.00 $155.00 $/Unit Monthly Usage Charge per 1,000 Gallons 0 - 8 kgal (Included in Monthly Base Rate Charge)N/A N/A N/A N/A N/A N/A $/kgal8 - 15 kgal $7.50 $7.50 $9.00 $10.80 $12.75 $14.80 $/kgal 15 - 30 kgal $9.00 $9.00 $10.80 $12.95 $15.30 $17.75 $/kgal >30 kgal $9.50 $9.50 $11.40 $13.70 $16.15 $18.75 $/kgal Hotels Monthly Base Rate Charge $54.00 $96.00 $115.00 $138.00 $163.00 $189.00 $/Unit Monthly Usage Charge per 1,000 Gallons 0 - 8 kgal (Included in Monthly Base Rate Charge)N/A N/A N/A N/A N/A N/A $/kgal 8 - 15 kgal $7.50 $8.85 $10.60 $12.75 $15.05 $17.45 $/kgal 15 - 30 kgal $9.00 $10.35 $12.40 $14.90 $17.60 $20.40 $/kgal >30 kgal $9.50 $10.85 $13.00 $15.60 $18.45 $21.40 $/kgal Private Haulers, $ per 500 Gallons Septage and Cesspool $64.00 $100.00 $140.00 $180.00 $217.00 $252.00 $/500 gal Portable Toilets $64.00 $84.00 $104.00 $127.00 $150.00 $174.00 $/500 gal WWTP $64.00 $95.00 $125.00 $155.00 $173.00 $201.00 $/500 gal Wastewater Rate Study – County of Hawai’i, Wastewater Division Section 4 4-3 County of HAWAII Wastewater Rate Study Report 08102026 A Figure 4-1. Single-Unit Residential Monthly Wastewater Bill Comparison Source Documentation: Maui: https://www.mauicounty.gov/811/Residential-Fees Kauai: https://www.kauai.gov/files/assets/public/v/1/public-works/wastewater-management/documents/approved-bill-no-2874- amended-relating-to-sewers.pdf City and County of Honolulu: https://www.honolulu.gov/env/sewer-fee-rates/ West Hawaii Sewer Company: https://www.hawaiiwaterservice.com/rates/rates-and-tariffs/waikoloa-village-rate-schedules/ Table 4-3. Monthly Bill Comparison For Single-Unit Residences Notes: (1) Italicized values are the proposed rates. (2) For Maui, City and County of Honolulu, and West Hawaii Sewer Company, monthly bills are based on monthly water consumption of 9 kgal/month. (3) Kauai and City and County of Honolulu have adopted rate increases that become effective in the future. Adopted future rates are shown in this table. (4) For the Waikoloa Village sewer system. Does not include a Power Cost Charge, which changes on a monthly basis. $0 $20 $40 $60 $80 $100 $120 $140 $160 $180 $200 $220 2025 2026 2027 2028 2029 2030 2031 Monthly Wastewater Bill Comparison, Single-Unit Residence, Water Use of 9 kgal/month COH Proposed Maui Kauai C&C HNL West Hawaii Sewer Co. Monthly Wastewater Bill as of July 1 of Each Year 2025 2026 2027 2028 2029 2030 2031 County of Hawaii (Proposed rates) (1)$52.00 $52.00 $63.00 $76.00 $91.00 $108.00 $125.00 County of Maui (2)$92.40 $103.75 County of Kauai (3)$73.75 $82.00 $91.00 $101.00 City and County of Honolulu (2) (3)$110.89 $133.45 $144.75 $157.81 $171.95 $187.48 $204.31 West Hawaii Sewer Company (4)$97.10 $113.98 $142.62 5-1 County of HAWAII Wastewater Rate Study Report 08102026 A Section 5 Ongoing Considerations and Recommendations There are a number of factors that could change over the next few years that have financial implications. The extent to which these factors change will influence the financial condition of the wastewater system and the Division’s next review of wastewater rates. The Division should continue to monitor its financial status on an ongoing basis, and should continue to monitor the following: • Development activity in the Division’s service area. A 1.0 percent annual system growth rate is projected through FY 30/31. New connections will increase the size of the Division’s customer base and result in increased wastewater rate revenues. Deviations in the actual growth rate from the projections in this Rate Study will have financial impacts that the Division should monitor over time. • Inflation rates. The projected rates are based on a 2.5 percent annual inflation rate for most items, noting that personnel expenses are projected to increase at a 5.0 percent annual rate. Deviations in inflation rates from these values will have financial implications. • O&M costs after completion of AOC capital projects. The Division is currently constructing upgrades at the Hilo WWTP, and an upgrade of the Kealakehe WWTP is planned. When these projects are complete, the costs to operate and maintain them will change. The Division should monitor O&M costs as these projects come online. • Impact Fees. The County should consider adopting a wastewater Impact Fee. An Impact Fee is a one-time that is charged to new customers connecting to the wastewater system. This fee is how new customers pay for their fair share of existing wastewater infrastructure. Wastewater Rate Study – County of Hawai’i, Wastewater Division A-1 County of HAWAII Wastewater Rate Study Report 08102026 A Section 6 Appendix A: Revenue Requirement Analysis Main Page County of Hawai`i Wastewater Division 2026 Wastewater Rate Study August 10, 2026 Appendix A: Revenue Requirement Analysis Appendix B: Cost-of-Service Analysis and Rate Design Table 1 General Assumptions and Parameters Table COS-1 Cost-of-Service Analysis - Functionalization of Projected FY 26/27 O&M Expenses Table 2 Existing Wastewater Service Charges Table COS-2 Cost-of-Service Analysis - Allocation of Rate Revenue Requirement Table 3a Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater Table COS-3 Cost-of-Service Analysis - Distribution of Rate Revenue Requirement Table 3b Summary of Projected Wastewater Flow by Customer Class Table COS-4 Cost-of-Service Based Rate Design Calculations Table 3c Projected BOD by Customer Class Table COS-5 Cost-of-Service Wastewater Service Charges (Before Rounding and Adjustments) Table 3d Projected TSS by Customer Class Table COS-6 Backcalculation of Revenues Under Cost-of-Service Wastewater Service Charges Table 4a Projected Revenues Under Existing Rate Schedule Table COS-7 Adjustments to Cost-of-Service Based Wastewater Service Charges Table 4b Revenue Backcalculation Table COS-8 Proposed Wastewater Service Charges (Not Rounded) Table 5 Projected O&M Expenses Table COS-9 Proposed and Projected Wastewater Service Charges (Rounded) Table 6 Not Used Table COS-10 Proposed and Projected Wastewater Service Charges: Percent Changes Table 7 Not Used Table COS-11 Backcalculation of Revenues Under Proposed Wastewater Service Charges Table 8 Projected Operating Statement Appendix C: Rate Study Supporting Calculations COH Wastewater Rate Model 08102026 Main Page Copyright 2026 All Rights Reserved 8/10/2026 Page 1 of 26 Appendix A - Dashboard County of Hawai`i Wastewater Division Wastewater Rate Study Dashboard UPDATED AUGUST 2026 REVENUE INCREASES FOR THE TEN-YEAR STUDY PERIOD Projected (Rate Revenue Increases Effective Each Jan 1) FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 FY 31/32 FY 32/33 FY 33/34 FY 34/35 % Wastewater Rate Revenue Increase 0.0%20.0%20.0%20.0%18.0%16.0%10.0%5.0%5.0%5.0% General Fund Transfer, $M $3.9 $6.8 $4.4 $0.8 $0.0 $0.0 $0.0 $0.0 $0.0 Available for Other Purposes, $M $0.0 $0.0 $0.0 $0.0 $3.1 $7.5 $10.3 $12.1 $13.9 KEY ASSUMPTIONS FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 FY 31/32 FY 32/33 FY 33/34 FY 34/35 System Growth, Excl System Extensions 1.0%1.0%1.0%1.0%1.0%1.0%1.0%1.0%1.0%1.0% Inflation 2.5%2.5%2.5%2.5%2.5%2.5%2.5%2.5%2.5%2.5% Personnel Inflation 5.0%5.0%5.0%5.0%5.0%5.0%5.0%5.0%5.0%5.0% Facilities Repairs, $M $0.5 $3.4 $2.0 $3.0 $4.0 $5.0 $5.0 $5.0 $5.0 $5.0 AOC Capital, $M No $1.0 $2.0 $3.0 $4.0 $5.0 $5.0 $5.0 $5.0 $5.0 System Extensions, $M $0.0 $0.0 $0.0 $0.0 $0.0 $0.0 $0.0 $0.0 $0.0 KEY ASSUMPTIONS APPLICABLE TO MULTIPLE YEARS S&W Underspend, FY 27/28 and Later 15.0% New EDUs per $1M in System Extensions 80 S&W Underspend, FY 26/27 20.0% Other Underspend, FY 26/27 and Later 7.0% 1/1/2026 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 1/1/2032 1/1/2033 1/1/2034 1/1/2035 10-Yr Total Monthly Rate, $/SFR $52.00 $63.00 $76.00 $91.00 $108.00 $125.00 $137.00 $144.00 $152.00 $159.00 General Fund Transfer, $M $6.4 $3.9 $7.0 $4.7 $1.4 $0.0 $0.0 $0.0 $0.0 $0.0 $23.2 $0.0 $1.0 $2.0 $3.0 $4.0 $5.0 $6.0 $7.0 $8.0 FY 2 6 / 2 7 FY 2 7 / 2 8 FY 2 8 / 2 9 FY 2 9 / 3 0 FY 3 0 / 3 1 Projected General Fund Transfer, $M $40 $50 $60 $70 $80 $90 $100 $110 $120 $130 1/ 1 / 2 0 2 6 1/ 1 / 2 0 2 7 1/ 1 / 2 0 2 8 1/ 1 / 2 0 2 9 1/ 1 / 2 0 3 0 1/ 1 / 2 0 3 1 Projected Sewer Rate, Single-Unit Residence COH Wastewater Rate Model 08102026 Dashboard Copyright 2026 All Rights Reserved Page 2 of 26 8/10/2026 Appendix A - Assumptions Table 1 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study General Assumptions and Parameters General Assumptions and Parameters Notes Debt Issuance Terms Notes 1 Round -1 GO Debt Terms 14, 15 2 Fiscal Year Begins July 1 Interest 5.0% 3 Costs of Issuance 1.0% 4 Inflation See Dashboard Term 25 5 Personnel Inflation See Dashboard 1 First Debt Service Payment is the Year Following Debt Issuance 6 Interest Income on Reserves 0.0%2 7 Employee Benefits and FICA, as % of S&W 43.0%3 8 Annual % Growth, Existing Collection System 1.0%4 SRF Debt Terms 15, 16 9 S&W/Personnel Underspend 15.0%5 Interest 2.5% 10 Other O&M Expense Underspend 7.0%6 Costs of Issuance 1.0% 11 New EDUs per $1M system extensions 80 7 Term 25 12 First Debt Service Payment is the Year Following Debt Issuance 13 Flow and Loading Assumptions 14 Single Family Residential per-unit sewage flow, gpd (8)204 15 Multi-Family Residential per-unit sewage flow, gpd (8)204 Key Revenue Assumptions 16 Percent of Hauler Volume from the Following Customer Classes (9)Projections are based on actual revenues from FY 24/25 escalated for projected system growth. 17 Septage 60.91%1.0 percent annual customer growth is projected, which is the approximate annual system growth 18 Cesspool 9.22%between 2018 and 2023. 19 Portable Toilet 11.64%The Sewer Fund receives an annual transfer from the County's General Fund to pay expenses, as 20 WWTP 18.23%Wastewater Service Charge revenues are currently not sufficient to pay Wastewater Division expenses. 21 Non-Residential Irrigation (10)8.0%The General Fund Transfer for FY 26/27 is per the COH draft FY 26/27 Budget. In all other years, 22 the General Fund Transfer is calculated. See notes in Table 8, Projected Operating Statement. 23 BOD mg/L TSS mg/L 24 Residential (11)198 141 Other O&M Expense Assumptions 25 Non-Residential Not Otherwise Specified (11)198 141 FY 26/27 O&M expenses per the COH draft FY 26/27 budget. 26 Hotels (12)310 141 FY 27/28 O&M expenses per the COH draft FY 27/28 budget except for wastewater equipment which 27 Haulers (13)remain at FY 26/27 budgeted amounts. 28 Septage 441 22,406 Inflation and underspend assumptions are applied to O&M expenses. 29 Cesspool 441 22,406 Some expenses such as electricity and chemicals are also adjusted by the projected system growth rate. 30 Portable Toilet 627 14,040 31 WWTP 949 16,500 Line No COH Wastewater Rate Model 08102026 T1Assumpt Copyright 2026 All Rights Reserved 8/10/2026 Page 3 of 26 Appendix A - Assumptions Table 1 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study General Assumptions and Parameters Table 1 Notes: (1) Acknowledges that personnel costs are increasing faster than the rate of General Inflation (2) All interest income is returned to the General Fund, in light of ongoing General Fund contributions to the Wastewater Utility. For purposes of a Wastewater Utility financial plan and Rate Study, the interest income is 0%. (3) Source: calculated based on the Division's FY 24/25 budget. (4) Calculated based on annual percent growth in billing units between February 2018 and November 2023 (5.75 years) of 0.93%, rounded to 1%. See Table 3a, Historical Number of Accounts, Number of Billing Units, and Chargeable Wastewater, for more detail. (5) S&W means salaries and wages. Starting FY 27/28, per COH staff, 4/1/2026. FY 26/27 projected underspend of 20%. (6) Starting FY 26/27, per COH staff, 4/1/2026. (7) Rate revenues are not projected to be sufficient to fund system extensions. Placeholder developed in 2024 during the assessment of rate revenue sufficiency: $1,300/LF per COH staff 8/13/2024. $1M gets about 4,000 LF. At 100 LF frontage and houses on both sides of street, this is 80 connections. (8) Sewer flow estimates from residences specific to Hawaii County are not available. Estimates from Kauai's past wastewater rate studies are used for the purposes of this Rate Study. County policy direction is to have the same sewer rate for single family and multi-family residential. (9) Source: septage hauler data from calendar year 2022. (10) Metered water used as a basis for wastewater charges is adjusted to recognize that some water use is not directed to the sewer system. The percentage is calculated so that systemwide total wastewater flow approximately equals actual plant wastewater flows. (11) BOD and TSS data from specific customers is not available. Data shown is calculated so that calculated BOD loadings and TSS loadings approximately match loadings from treatment plant influent data, based on FY 22/23 data. (12) BOD data is used in County of Kaua`i's 2022 Rate Study, for hotels without restaurants. TSS data equals that of other non-residential customers. (13) Source: data contained in COH Local Limits Presentation, March 19, 2025, received from COH staff 4/22/2024. The data in the local limits presentation is taken in Hilo and is applied to customers throughout the County's wastewater service area. (14) Source: COH staff 2/8/24 embedded in "New Fee Generated.xls" spreadsheet related to potential Kaumana Gardens extension. (15) Provided for illustrative purposes only. This Rate Study does not assume that any future debt issuances are paid by wastewater rates, so debt issuance terms do not affect wastewater rate calculations. (16) Approximate historical terms for SRF loans. COH Wastewater Rate Model 08102026 T1Assumpt Copyright 2026 All Rights Reserved 8/10/2026 Page 4 of 26 Appendix A - Existing Rates Table 2 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Existing Wastewater Service Charges Monthly Base Usage Line Rate Charge Charge per No.Customer Class Per Unit 1,000 gallons Discharge Fee Units 1 Single Unit Residential $52.00 Per Unit 2 3 Multi-Unit Residential $52.00 Per Unit 4 5 Non-Residential $54.00 Per Unit 6 0 - 8 kgal/month $0.00 Per kgal/month 7 8 - 15 kgal/month $7.50 Per kgal/month 8 15 - 30 kgal/month $9.00 Per kgal/month 9 >30 kgal/month $9.50 Per kgal/month 10 11 Private Haulers $64.00 Per 500 gallons 12 13 Gang Cesspools $25.00 Per Unit Source: County of Hawai`i Ordinance No. 1921, adopted February 20, 2019. Rates shown have been effective since 4/1/2023. COH Wastewater Rate Model 08102026 T2ExistRates Copyright 2026 All rights reserved 8/10/2026 Page 5 of 26 Appendix A - Billing Units Table 3 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 3a: Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater Line Nov 30 Projected No.2023 FY 23/24 FY 24/25 FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 1 Number of Accounts (1) 2 Hilo 3 Single-Unit Residence 1,830 1,830 1,848 1,866 1,885 1,904 1,923 1,942 1,961 4 Multi-Unit Residence 121 121 122 123 124 125 126 127 128 5 Non-Residential 696 696 703 710 717 724 731 738 745 6 Honokaa 7 Single-Unit Residence 34 34 34 34 34 34 34 34 34 8 Multi-Unit Residence 5 5 5 5 5 5 5 5 5 9 Non-Residential 70 70 71 72 73 74 75 76 77 10 Kapehu 11 Single-Unit Residence 29 29 29 29 29 29 29 29 29 12 Kona 13 Single-Unit Residence 1,681 1,681 1,698 1,715 1,732 1,749 1,766 1,784 1,802 14 Multi-Unit Residence 141 141 142 143 144 145 146 147 148 15 Non-Residential 209 209 211 213 215 217 219 221 223 16 Kulaimano 17 Single-Unit Residence 457 457 462 467 472 477 482 487 492 18 Multi-Unit Residence 3 3 3 3 3 3 3 3 3 19 Non-Residential 4 4 4 4 4 4 4 4 4 20 Naalehu 21 Gang Cesspool 146 146 147 148 149 150 152 154 156 22 Pahala 23 Gang Cesspool 100 100 101 102 103 104 105 106 107 24 Papaikou 25 Single-Unit Residence 444 444 448 452 457 462 467 472 477 26 Non-Residential 16 16 16 16 16 16 16 16 16 27 Total 5,986 5,986 6,044 6,102 6,162 6,222 6,283 6,345 6,407 28 29 Number of Accounts by Customer Type 30 Single-Unit Residence 4,475 4,475 4,519 4,563 4,609 4,655 4,701 4,748 4,795 31 Multi-Unit Residence 270 270 272 274 276 278 280 282 284 32 Non-Residential 995 995 1,005 1,015 1,025 1,035 1,045 1,055 1,065 33 Gang Cesspool 246 246 248 250 252 254 257 260 263 34 Total 5,986 5,986 6,044 6,102 6,162 6,222 6,283 6,345 6,407 35 TRUE COH Wastewater Rate Model 08102026 T3Units Copyright 2026 All rights reserved 8/10/2026 Page 6 of 26 Appendix A - Billing Units Table 3 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 3a: Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater 36 Number of Billing Units (1) 37 Hilo 38 Single-Unit Residence 2,007 2,007 2,027 2,047 2,067 2,088 2,109 2,130 2,151 39 Multi-Unit Residence 3,435 3,435 3,469 3,504 3,539 3,574 3,610 3,646 3,682 40 Non-Residential 980 980 990 1,000 1,010 1,020 1,030 1,040 1,050 41 Honokaa 42 Single-Unit Residence 37 37 37 37 37 37 37 37 37 43 Multi-Unit Residence 65 65 66 67 68 69 70 71 72 44 Non-Residential 107 107 108 109 110 111 112 113 114 45 Kapehu 46 Single-Unit Residence 29 29 29 29 29 29 29 29 29 47 Kona 48 Single-Unit Residence 1,728 1,728 1,745 1,762 1,780 1,798 1,816 1,834 1,852 49 Multi-Unit Residence 4,816 4,816 4,864 4,913 4,962 5,012 5,062 5,113 5,164 50 Non-Residential 282 282 285 288 291 294 297 300 303 51 Kulaimano 52 Single-Unit Residence 457 457 462 467 472 477 482 487 492 53 Multi-Unit Residence 178 178 180 182 184 186 188 190 192 54 Non-Residential 4 4 4 4 4 4 4 4 4 55 Naalehu 56 Gang Cesspool 146 146 147 148 149 150 152 154 156 57 Pahala 58 Gang Cesspool 100 100 101 102 103 104 105 106 107 59 Papaikou 60 Single-Unit Residence 450 450 455 460 465 470 475 480 485 61 Non-Residential 16 16 16 16 16 16 16 16 16 62 Total 14,837 14,837 14,985 15,135 15,286 15,439 15,594 15,750 15,906 63 TRUE 64 Number of Billing Units by Customer Type 65 Single-Unit Residence 4,708 4,708 4,755 4,802 4,850 4,899 4,948 4,997 5,046 66 Multi-Unit Residence 8,494 8,494 8,579 8,666 8,753 8,841 8,930 9,020 9,110 67 Non-Residential and Hotels 1,389 1,389 1,403 1,417 1,431 1,445 1,459 1,473 1,487 68 Gang Cesspool 246 246 248 250 252 254 257 260 263 69 Total 14,837 14,837 14,985 15,135 15,286 15,439 15,594 15,750 15,906 70 COH Wastewater Rate Model 08102026 T3Units Copyright 2026 All rights reserved 8/10/2026 Page 7 of 26 Appendix A - Billing Units Table 3 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 3a: Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater 71 Non-Residential Chargeable Wastewater, kgal/year (2) 72 Hilo 301,208 301,208 304,220 307,262 310,335 313,438 316,572 319,738 322,935 73 Honokaa 11,624 11,624 11,740 11,857 11,976 12,096 12,217 12,339 12,462 74 Kona 275,336 275,336 278,089 280,870 283,679 286,516 289,381 292,275 295,198 75 Pahala 188 188 190 192 194 196 198 200 202 76 Papaikou 3,027 3,027 3,057 3,088 3,119 3,150 3,182 3,214 3,246 77 Total 591,382 591,382 597,296 603,269 609,303 615,396 621,550 627,766 634,043 78 79 Non-Res. Chargeable Water by Rate Tier, kgal/year (2) 80 Tier 1: 0 - 8 kgal/month (3) 81 Hilo 28,733 28,733 29,020 29,310 29,603 29,899 30,198 30,500 30,805 82 Honokaa 2,529 2,529 2,554 2,580 2,606 2,632 2,658 2,685 2,712 83 Kona 8,804 8,804 8,892 8,981 9,071 9,162 9,254 9,347 9,440 84 Pahala 67 67 68 69 70 71 72 73 74 85 Papaikou 807 807 815 823 831 839 847 855 864 86 Subtotal Tier 1 40,940 40,940 41,349 41,763 42,181 42,603 43,029 43,460 43,895 87 88 Tier 2: 8 - 15 kgal/month (4) 89 Hilo 17,755 17,755 17,933 18,112 18,293 18,476 18,661 18,848 19,036 90 Honokaa 1,408 1,408 1,422 1,436 1,450 1,465 1,480 1,495 1,510 91 Kona 7,047 7,047 7,117 7,188 7,260 7,333 7,406 7,480 7,555 92 Pahala 41 41 41 41 41 41 41 41 41 93 Papaikou 310 310 313 316 319 322 325 328 331 94 Subtotal Tier 2 26,561 26,561 26,826 27,093 27,363 27,637 27,913 28,192 28,473 95 96 Tier 3: 15 - 30 kgal/month (5) 97 Hilo 27,121 27,121 27,392 27,666 27,943 28,222 28,504 28,789 29,077 98 Honokaa 1,769 1,769 1,787 1,805 1,823 1,841 1,859 1,878 1,897 99 Kona 13,416 13,416 13,550 13,686 13,823 13,961 14,101 14,242 14,384 100 Pahala 66 66 67 68 69 70 71 72 73 101 Papaikou 356 356 360 364 368 372 376 380 384 102 Subtotal Tier 3 42,728 42,728 43,156 43,589 44,026 44,466 44,911 45,361 45,815 103 COH Wastewater Rate Model 08102026 T3Units Copyright 2026 All rights reserved 8/10/2026 Page 8 of 26 Appendix A - Billing Units Table 3 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 3a: Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater 104 Tier 4: >30 kgal/month (6) 105 Hilo 227,599 227,599 229,875 232,174 234,496 236,841 239,209 241,601 244,017 106 Honokaa 5,918 5,918 5,977 6,037 6,097 6,158 6,220 6,282 6,345 107 Kona 246,069 246,069 248,529 251,014 253,524 256,059 258,620 261,206 263,818 108 Pahala 14 14 14 14 14 14 14 14 14 109 Papaikou 1,554 1,554 1,569 1,585 1,601 1,617 1,633 1,649 1,665 110 Subtotal Tier 4 481,153 481,153 485,964 490,824 495,732 500,689 505,696 510,752 515,859 111 Math Check, Should = 0 0 0 1 0 1 1 1 1 1 112 113 Hotels Chargeable Water, kgal/year 114 Hilo 62,704 62,704 62,704 62,704 62,704 62,704 62,704 62,704 62,704 115 Honokaa 212 212 212 212 212 212 212 212 212 116 Kona 53,059 53,059 53,059 53,059 53,059 53,059 53,059 53,059 53,059 117 Total 115,976 115,976 115,976 115,976 115,976 115,976 115,976 115,976 115,976 118 119 Hotels Chargeable Water by Rate Tier, kgal/year (7) 120 Tier 1: 0 - 8 kgal/month (3) 121 Hilo 576 576 582 588 594 600 606 612 618 122 Honokaa 48 48 48 48 48 48 48 48 48 123 Kona 568 568 574 580 586 592 598 604 610 124 Subtotal Tier 1 1,192 1,192 1,204 1,216 1,228 1,240 1,252 1,264 1,276 125 126 Tier 2: 8 - 15 kgal/month (4) 127 Hilo 479 479 484 489 494 499 504 509 514 128 Honokaa 42 42 42 42 42 42 42 42 42 129 Kona 497 497 502 507 512 517 522 527 532 130 Subtotal Tier 2 1,018 1,018 1,028 1,038 1,048 1,058 1,068 1,078 1,088 131 132 Tier 3: 15 - 30 kgal/month (5) 133 Hilo 919 919 928 937 946 955 965 975 985 134 Honokaa 89 89 90 91 92 93 94 95 96 135 Kona 1,008 1,008 1,018 1,028 1,038 1,048 1,058 1,069 1,080 136 Subtotal Tier 3 2,016 2,016 2,036 2,056 2,076 2,096 2,117 2,139 2,161 137 138 Tier 4: >30 kgal/month (6) 139 Hilo 60,730 60,730 61,337 61,950 62,570 63,196 63,828 64,466 65,111 140 Honokaa 33 33 33 33 33 33 33 33 33 141 Kona 50,986 50,986 51,496 52,011 52,531 53,056 53,587 54,123 54,664 142 Subtotal Tier 4 111,750 111,750 112,866 113,994 115,134 116,285 117,448 118,622 119,808 COH Wastewater Rate Model 08102026 T3Units Copyright 2026 All rights reserved 8/10/2026 Page 9 of 26 Appendix A - Billing Units Table 3 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 3a: Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater Table 3a Notes: (1) Source: COH staff, data for November 2023. (2) Source: COH staff, 2/4/2024, using data from FY 22/23. Data provided was non-residential metered consumption for each billing period during FY 22/23. (3) Consumption in the 0-8 kgal/month tier is total water use for customers using <8 kgal/month plus 8 kgal/month for customers using > 8 kgal/month. (4) Consumption in the 8 - 15 kgal/month tier is water use between 8 and 15 kgal/month for customers using between 8 and 15 kgal/month plus 7 kgal/month for customers using more than 15 kgal/month. (5) Consumption in the 15 - 30 kgal/month tier is water use between 15 and 30 kgal/month for customers using between 15 and 30 kgal/month plus 15 kgal/month for customers using more than 30 kgal/month. (6) Consumption in the >30 kgal/month tier is water use exceeding 30 kgal/month. (7) Hotels identified by FG Solutions based on a review of account names and addresses. This identification is developed for rate setting only, and not for billing purposes. COH must identify hotels in its service area for billing purposes. COH Wastewater Rate Model 08102026 T3Units Copyright 2026 All rights reserved 8/10/2026 Page 10 of 26 Appendix A - Billing Units Table 3 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 3a: Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater Table 3b: Summary of Projected Wastewater Flow by Customer Class Line Projected Sewer Flow, kgal/year (1) No.Customer Class FY 24/25 FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 1 Residential (Single-Unit) (2)354,057 357,557 361,131 364,780 368,428 372,077 375,725 2 Residential (Multi-Unit) (2)638,792 645,270 651,748 658,301 664,928 671,629 678,331 3 Gang Cesspools (2)18,466 18,615 18,764 18,913 19,136 19,360 19,583 4 Non-Residential Sewer Flow Allowance in Base Rate 5 Non-Residential 41,349 41,763 42,181 42,603 43,029 43,460 43,895 6 Hotels 582 588 594 600 606 612 618 7 8 Non-Residential Billed Sewer Flow (Above Base Rate Allowance) 9 Non-Residential 555,946 561,506 567,121 572,792 578,520 584,305 590,147 10 Hotels 115,930 117,088 118,258 119,439 120,633 121,839 123,057 11 12 Private Haulers (3) 13 Septage 3,393 3,427 3,461 3,496 3,531 3,566 3,602 14 Cesspool 513 519 524 529 534 539 544 15 Portable Toilets 649 655 662 669 676 683 690 16 WWTP 1,015 1,025 1,035 1,045 1,055 1,066 1,077 17 Total 1,730,693 1,748,013 1,765,479 1,783,166 1,801,076 1,819,135 1,837,269 18 Compare with FY 22/23 WWTP Data (4)1,731,542 19 Percent Difference 0% Notes: (1) Wastewater flows are projected to increase at the rate of system growth. (2) Equals the number of billing units multiplied by the sewage flow per unit. (3) Based on hauler data for calendar year 2022 provided by COH staff. (4) This comparison to wastewater treatment plant influent flows is used to validate the residential sewage flow assumptions. COH Wastewater Rate Model 08102026 T3Units Copyright 2026 All rights reserved 8/10/2026 Page 11 of 26 Appendix A - Billing Units Table 3 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 3a: Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater Table 3c: Projected BOD by Customer Class Line Projected BOD (lbs/year) (1) (2) No.Customer Class FY 24/25 FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 1 Residential (Single-Unit)584,967 590,749 596,654 602,682 608,710 614,738 620,767 2 Residential (Multi-Unit) 1,055,402 1,066,104 1,076,807 1,087,633 1,098,582 1,109,654 1,120,726 3 Gang Cesspools 30,509 30,755 31,001 31,247 31,617 31,986 32,355 4 Non-Residential 5 Non-Residential Not Otherwise Stated 986,840 996,711 1,006,678 1,016,745 1,026,912 1,037,182 1,047,553 6 Hotels 301,387 304,398 307,440 310,511 313,615 316,750 319,916 7 Private Haulers 8 Septage 12,486 12,611 12,736 12,865 12,994 13,122 13,255 9 Cesspool 1,889 1,910 1,928 1,947 1,965 1,983 2,002 10 Portable Toilets 3,392 3,426 3,462 3,499 3,536 3,572 3,609 11 WWTP 8,036 8,112 8,192 8,271 8,350 8,437 8,524 12 Total 2,984,909 3,014,777 3,044,900 3,075,400 3,106,281 3,137,426 3,168,706 13 Compare with FY 22/23 WWTP Data 2,980,951 Notes: (1) BOD loading in lb/year is calculated separately by customer class by multiplying the projected wastewater flow by the estimated BOD concentration. (2) BOD loadings are projected to increase at the rate of system growth. Table 3d: Projected TSS by Customer Class Line Historical and Projected TSS (lbs/year) (1) (2) No.Customer Class FY 24/25 FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 1 Residential (Single-Unit)416,568 420,685 424,890 429,183 433,476 437,768 442,061 2 Residential (Multi-Unit)751,574 759,196 766,817 774,527 782,324 790,208 798,093 3 Gang Cesspools 21,726 21,902 22,077 22,252 22,515 22,778 23,040 4 Non-Residential 5 Non-Residential Not Otherwise Stated 702,750 660,642 667,249 673,921 680,660 687,467 694,340 6 Hotels 137,083 138,452 139,836 141,232 142,644 144,070 145,510 7 Private Haulers 8 Septage 634,360 640,724 647,081 653,625 660,169 666,712 673,443 9 Cesspool 95,994 97,034 97,969 98,904 99,839 100,773 101,708 10 Portable Toilets 75,986 76,736 77,556 78,377 79,197 80,017 80,837 11 WWTP 139,793 141,124 142,501 143,878 145,254 146,769 148,283 12 Total 2,975,833 2,956,496 2,985,976 3,015,898 3,046,077 3,076,562 3,107,316 13 Compare with FY 22/23 WWTP Data 2,979,825 COH Wastewater Rate Model 08102026 T3Units Copyright 2026 All rights reserved 8/10/2026 Page 12 of 26 Appendix A - Billing Units Table 3 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 3a: Historical and Projected Number of Accounts, Number of Billing Units, and Chargeable Wastewater Table 3d Notes: (1) TSS loading in lb/year is calculated separately by customer class by multiplying the projected wastewater flow by the estimated TSS concentration. (2) TSS loadings are projected to increase at the rate of system growth. COH Wastewater Rate Model 08102026 T3Units Copyright 2026 All rights reserved 8/10/2026 Page 13 of 26 Appendix A - Revenues Table 4 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 4a: Projected Revenues Under Existing Rate Schedule Line Actual Calculated Actual Projected (Actual FY 24/25 Revenues Plus Projected System Growth) No.FY 23/24 (1)FY 23/24 (y)FY 24/25 (1)FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 1 Rate Revenues by System 2 Hilo $7,086,718 $6,570,290 $7,240,840 $7,313,248 $7,386,381 $7,460,245 $7,534,847 $7,610,195 $7,686,297 3 Honokaa $185,789 $215,688 $176,023 $177,783 $179,561 $181,357 $183,170 $185,002 $186,852 4 Kapehu $15,814 $18,096 $17,654 $17,831 $18,009 $18,189 $18,371 $18,555 $18,740 5 Kona $7,181,584 $6,777,442 $7,209,929 $7,282,028 $7,354,848 $7,428,397 $7,502,681 $7,577,707 $7,653,484 6 Kulaimano $413,078 $399,863 $378,439 $382,223 $386,046 $389,906 $393,805 $397,743 $401,721 7 Naalehu $40,565 $43,800 $42,232 $42,654 $43,081 $43,512 $43,947 $44,386 $44,830 8 Pahala $32,122 $30,000 $30,333 $30,636 $30,943 $31,252 $31,565 $31,880 $32,199 9 Papaikou $300,659 $311,458 $293,579 $296,515 $299,480 $302,475 $305,499 $308,554 $311,640 10 $15,256,328 $14,366,637 $15,389,029 $15,542,919 $15,698,348 $15,855,331 $16,013,885 $16,174,024 $16,335,764 11 12 Hauler Revenue 13 Hilo $349,555 $302,723 $305,751 $308,808 $311,896 $315,015 $318,165 $321,347 14 Kona $410,293 $439,941 $444,340 $448,784 $453,271 $457,804 $462,382 $467,006 15 Total $759,848 $742,664 $750,091 $757,592 $765,168 $772,819 $780,547 $788,353 16 17 Kaloko Reimb. (2)$295,498 $322,501 $322,501 $322,501 $322,501 $322,501 $322,501 $322,501 18 19 Vacation Transfers (3)$962 $0 $0 $0 $0 $0 $0 $0 20 21 Total $16,312,635 $16,454,194 $16,615,510 $16,778,441 $16,943,000 $17,109,205 $17,277,072 $17,446,618 22 Math Check (4)($0)$0 Notes: (1) Source: COH staff, received 2/5/2026. Filenames Revstat Fy 23-24.pdf and Revstat FY 25/26.pdf (2) Revenue is to reimburse COH staff for services at the Kaloko WWTP, and is projected to remain at FY 24/25 levels through FY 30/31. (3) Revenue from this non-recurring revenue are projected to be $0 through the Rate Study Planning Period (4) Math check verifies that the total in this table equals the source data (Rev Status Report less GF Transfer). Value should = $0 COH Wastewater Rate Model 08102026 T4 Revenues Copyright 2026 All rights reserved 8/10/2026 Page 14 of 26 Appendix A - Revenues Table 4 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 4b: Revenue Backcalculation Line Calculated Projected Based on Calculation, Not Used in Revenue Requirement/Operating Statement (1) No.FY 23/24 (y)FY 24/25 FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 1 Charges for Services 2 Single-Unit Residential 3 Hilo $1,252,368 $1,264,892 $1,277,541 $1,290,316 $1,303,219 $1,316,251 $1,329,414 $1,342,708 4 Honokaa $23,088 $23,319 $23,552 $23,788 $24,025 $24,266 $24,508 $24,753 5 Kapehu $18,096 $18,277 $18,460 $18,644 $18,831 $19,019 $19,209 $19,401 6 Kona $1,078,272 $1,089,055 $1,099,945 $1,110,945 $1,122,054 $1,133,275 $1,144,607 $1,156,054 7 Kulaimano $285,168 $288,020 $290,900 $293,809 $296,747 $299,714 $302,712 $305,739 8 Papaikou $280,800 $283,608 $286,444 $289,309 $292,202 $295,124 $298,075 $301,056 9 Multi-Unit Residential 10 Hilo $2,143,440 $2,164,874 $2,186,523 $2,208,388 $2,230,472 $2,252,777 $2,275,305 $2,298,058 11 Honokaa $40,560 $40,966 $41,375 $41,789 $42,207 $42,629 $43,055 $43,486 12 Kapehu 13 Kona $3,005,184 $3,035,236 $3,065,588 $3,096,244 $3,127,207 $3,158,479 $3,190,063 $3,221,964 14 Kulaimano $111,072 $112,183 $113,305 $114,438 $115,582 $116,738 $117,905 $119,084 15 Papaikou 16 Non-Residential Monthly Base Rate 17 Hilo $635,040 $641,390 $647,804 $654,282 $660,825 $667,433 $674,108 $680,849 18 Honokaa $69,336 $70,029 $70,730 $71,437 $72,151 $72,873 $73,602 $74,338 19 Kona $182,736 $184,563 $186,409 $188,273 $190,156 $192,057 $193,978 $195,918 20 Kulaimano $2,592 $2,618 $2,644 $2,671 $2,697 $2,724 $2,751 $2,779 21 Papaikou $10,368 $10,472 $10,576 $10,682 $10,789 $10,897 $11,006 $11,116 COH Wastewater Rate Model 08102026 T4 Revenues Copyright 2026 All rights reserved 8/10/2026 Page 15 of 26 Appendix A - Revenues Table 4 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table 4b: Revenue Backcalculation (Continued) Line Calculated Projected Based on Calculation, Not Used in Revenue Requirement/Operating Statement (1) No.FY 23/24 (y)FY 24/25 FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 22 Non-Residential Usage Charges 23 Tier 1 $0 $0 $0 $0 $0 $0 $0 $0 24 Tier 2 25 Hilo $133,163 $134,494 $135,839 $137,197 $138,569 $139,955 $141,355 $142,768 26 Honokaa $10,560 $10,666 $10,772 $10,880 $10,989 $11,099 $11,210 $11,322 27 Kona $52,853 $53,381 $53,915 $54,454 $54,999 $55,549 $56,104 $56,665 28 Kulaimano $308 $311 $314 $317 $320 $323 $326 $330 29 Papaikou $2,325 $2,348 $2,372 $2,395 $2,419 $2,444 $2,468 $2,493 30 Tier 3 31 Hilo $244,089 $246,530 $248,995 $251,485 $254,000 $256,540 $259,105 $261,696 32 Honokaa $15,921 $16,080 $16,241 $16,403 $16,567 $16,733 $16,900 $17,069 33 Kona $120,744 $121,951 $123,171 $124,403 $125,647 $126,903 $128,172 $129,454 34 Kulaimano $594 $600 $606 $612 $618 $624 $631 $637 35 Papaikou $3,204 $3,236 $3,268 $3,301 $3,334 $3,367 $3,401 $3,435 36 Tier 4 37 Hilo $2,162,191 $2,183,812 $2,205,651 $2,227,707 $2,249,984 $2,272,484 $2,295,209 $2,318,161 38 Honokaa $56,223 $56,785 $57,353 $57,927 $58,506 $59,091 $59,682 $60,279 39 Kona $2,337,653 $2,361,030 $2,384,640 $2,408,486 $2,432,571 $2,456,897 $2,481,466 $2,506,281 40 Kulaimano $130 $131 $133 $134 $135 $137 $138 $139 41 Papaikou $14,761 $14,909 $15,058 $15,208 $15,360 $15,514 $15,669 $15,826 42 Gang Cesspool Monthly Charge 43 Naalehu $43,800 $44,238 $44,680 $45,127 $45,578 $46,034 $46,495 $46,960 44 Pahala $30,000 $30,300 $30,603 $30,909 $31,218 $31,530 $31,846 $32,164 45 Total Rate Revenues $14,366,637 $14,510,304 $14,655,407 $14,801,961 $14,949,980 $15,099,480 $15,250,475 $15,402,980 Notes: (1) This revenue backcalculation is made to verify that the billing determinants are sufficiently accurate to produce calculated revenues that approximate actual revenues. COH Wastewater Rate Model 08102026 T4 Revenues Copyright 2026 All rights reserved 8/10/2026 Page 16 of 26 Appendix A - Projected O&M Expenses Table 5 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected O&M Expenses Line Actual Projected (2) No.Account FY 24/25 (1)FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes 1 Department 631 - Wastewater 2 Salaries and Wages 3 Regular S&W Hilo 4 Regular S&W Kona 5 Regular S&W Adm 6 Total Regular S&W $6,934,634 $8,162,678 $8,570,812 $8,999,352 $9,449,320 3 7 New Positions $375,000 $393,750 $413,438 3, 4 8 Total Regular S&W $3,984,370 $6,934,634 $8,162,678 $8,945,812 $9,393,102 $9,862,758 9 10 Overtime - Hilo 11 Overtime - Kona 12 Overtime - Adm 13 Callout - Hilo 14 Callout - Kona 15 Total Overtime S&W $416,234 $140,309 $140,309 $147,324 $154,691 $162,425 3 16 17 Miscellaneous 18 Temp Assignment - Hilo 19 Temp Assignment - Kona 20 Standby - Hilo 21 Standby - Kona 22 Other - Hilo 23 Other - Kona 24 Other - ADM 25 Total Miscellaneous S&W $781,226 $210,800 $210,800 $221,340 $232,407 $244,027 3 26 27 Total Salaries and Wages $5,181,830 $7,285,743 $8,513,787 $9,314,476 $9,780,200 $10,269,210 28 Math check should = 0 $0 29 30 Wastewater OCE 31 Postage 32 Freight 33 Total OCE Postage & Freight $40,926 $46,000 $46,000 $47,150 $48,329 $49,537 34 35 Telephone 36 Cellular 37 Telecomm/Data Lines COH Wastewater Rate Model 08102026 T5 O&M Copyright 2026 All rights reserved 8/10/2026 Page 17 of 26 Appendix A - Projected O&M Expenses Table 5 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected O&M Expenses Line Actual Projected (2) No.Account FY 24/25 (1)FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes 38 Total OCE Telephone $60,787 $66,000 $66,000 $67,650 $69,341 $71,075 39 40 Janitorial DPW 41 Grounds - ARC 42 Total OCE Janitorial $78,280 $90,000 $90,000 $92,250 $94,556 $96,920 43 44 Travel/Conferences InterIsland 45 Travel/Conferences IntraIsland 46 Out of State 47 Total OCE Travel/Conference $15,053 $42,000 $52,000 $53,300 $54,633 $55,998 48 49 Business Cards 50 Envelopes 51 Total OCE Printing $15,201 $21,100 $21,100 $21,628 $22,168 $22,722 52 53 Total OCE Advertising - Public Notices $1,425 $10,000 $5,000 $5,125 $5,253 $5,384 54 55 Office Equipment 56 Vehicle Repairs/Maintenance 57 Instrumentation 58 Line Equipment 59 Plant Equipment 60 Lab Equipment 61 Port Equipment 62 Facilities Annual Maintenance 63 Total Wastewater OCE Equip Repairs/Maint $260,377 $334,100 $334,100 $342,453 $351,014 $359,789 64 65 Building Maintenance 66 Admin-Office 67 Air Conditioner 68 Total OCE Repairs to Facilities $18,932 $920,000 $920,000 $943,000 $966,575 $990,739 69 70 Total OCE Rental/Lease of Equip $407,001 $585,491 $695,556 $712,945 $730,769 $749,038 71 72 CALL OUT MILEAGE - EAST 73 CALL OUT MILEAGE - WEST 74 Total OCE Mileage & Auto Allowance $234 $2,300 $2,300 $2,358 $2,416 $2,477 COH Wastewater Rate Model 08102026 T5 O&M Copyright 2026 All rights reserved 8/10/2026 Page 18 of 26 Appendix A - Projected O&M Expenses Table 5 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected O&M Expenses Line Actual Projected (2) No.Account FY 24/25 (1)FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes 75 76 Water - East 77 Water - West 78 Gas Utility - East 79 Total OCE Water, Gas and Sewer $155,746 $178,530 $178,530 $182,993 $187,568 $192,257 80 81 Electricity - East 82 Electricity - West 83 Electricity - Admin 84 Total OCE Electricity $2,933,751 $3,660,168 $3,660,168 $3,789,189 $3,922,758 $4,061,035 5 85 112 Total OCE Misc. Contract Services $765,348 $1,039,560 $1,508,560 $1,546,274 $1,584,931 $1,624,554 113 114 Tipping Fees 115 SWD Refuse Hauling 116 Total OCE Refuse Disposal $320,616 $830,000 $830,000 $859,258 $889,546 $920,903 5 117 118 Vegetation Control - East 119 Vegetation Control - West 120 Total OCE Agricultural Supplies $5,376 $6,000 $6,150 $6,304 $6,461 $6,623 121 122 Cleansers 123 Paper 124 Hardware 125 Polymer (GMP) 126 Odor Control (Carbon) 127 Caustic 128 Sodium Hypochlorite 129 Poly Aluminum Chloride (PAC) 130 Lime 131 Sodium Bisulfite 132 Chlorine 133 Misc Chemicals (Microbe Lift) 134 Total OCE Cleaning/Sanitation Supplies $725,698 $938,500 $938,500 $971,582 $1,005,830 $1,041,286 5 135 136 Unleaded 137 Lubricants COH Wastewater Rate Model 08102026 T5 O&M Copyright 2026 All rights reserved 8/10/2026 Page 19 of 26 Appendix A - Projected O&M Expenses Table 5 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected O&M Expenses Line Actual Projected (2) No.Account FY 24/25 (1)FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes 138 Solvents 139 Propane 140 Diesel 141 Total OCE Fuels & Lubricants $109,091 $137,500 $137,500 $140,938 $144,461 $148,072 142 143 Admin 144 Operations - East 145 Operations - West 146 Total OCE Computer & Office Supp $20,285 $24,700 $24,700 $25,318 $25,950 $26,599 147 148 Electrical/Electronics 149 Treatment/Disposal 150 Tires 151 Batteries 152 Filters 153 Vehicle Parts 154 Kaloko WWTP Spare Parts 155 Kealakehe WWTP Aeration Parts 156 Honokaa Spare Parts 157 Total OCE M.V./Hvy Eqpt Parts/Supp $363,915 $542,200 $542,200 $555,755 $569,649 $583,890 8 158 159 Maintenance 160 Laboratory 161 Collection System 162 Safety 163 Small Tools 164 Total OCE Misc. Materials & Supp $127,315 $373,400 $373,400 $382,735 $392,303 $402,111 4 165 166 Total Wastewater OCE Subscrip & Membership $99,145 $168,424 $168,424 $172,635 $176,950 $181,374 4 167 168 Total OCE, Building Rent $125,003 $135,000 $135,000 $138,375 $141,834 $145,380 4 169 170 Credit Card Fees $830,035 $830,035 $830,035 $830,035 $830,035 6 171 EM Admin Fees $346,411 $352,625 $382,191 $412,497 $443,560 6, 7 172 Total OCE Misc. Charges $830,035 $1,176,446 $1,182,660 $1,212,227 $1,242,532 $1,273,595 6 173 174 Total Wastewater OCE $7,479,539 $11,327,419 $11,917,848 $12,271,438 $12,635,829 $13,011,361 COH Wastewater Rate Model 08102026 T5 O&M Copyright 2026 All rights reserved 8/10/2026 Page 20 of 26 Appendix A - Projected O&M Expenses Table 5 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected O&M Expenses Line Actual Projected (2) No.Account FY 24/25 (1)FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes 175 Math check should = 0 $0 176 177 Wastewater Equipment 178 Pkup, 1T, 4WD Utility Truck (2) 179 4WD 4Door Utility Vehicle 180 F350 Utility Bed Truck 4WD 181 Wastewater Eqpt, Motor Vehicle $418,799 $640,000 $656,000 $672,400 $689,210 $706,440 8 182 183 Wastewater Eqpt, Office Equip-Fix-Furn $31,790 $8,500 $8,713 $8,930 $9,154 $9,382 8 184 185 Wastewater Eqpt, Computer Eqpt & Software $11,740 $22,100 $22,653 $23,219 $23,799 $24,394 8 186 187 Wastewater Eqpt, Misc Equipment <30K 188 Analytical Balance (3) 189 Flyght 215 HP Pump PUA 190 Utility ATV (2) Hilo 191 Utility ATV (2) Kona 192 Dewatering Container 8 CY (West) 193 Verbatim Alarms (12) 194 Multi Smarts (15) 195 Total Wastewater Eqpt, Misc Equipment $632,400 $2,995,000 $3,069,875 $3,146,622 $3,225,287 $3,305,920 8 196 197 Total Wastewater Equipment $1,094,728 $3,665,600 $3,757,240 $3,851,171 $3,947,450 $4,046,137 198 199 Annual Operator Training Fee 200 Total Operator Training Facility $0 $0 $0 $0 $0 $0 201 202 Total Clean Water Act 604(b), Reg S&W 203 204 Total Dept 631, Wastewater $13,756,098 $22,278,762 $24,188,875 $25,437,085 $26,363,480 $27,326,708 205 Math check should = 0 $0 206 207 Dept 901 - Pensions & Contributions 208 Employee Benefits & FICA 209 Health Benefits $529,960 210 Retirement Benefits $1,114,124 211 FICA Employer Share $385,617 COH Wastewater Rate Model 08102026 T5 O&M Copyright 2026 All rights reserved 8/10/2026 Page 21 of 26 Appendix A - Projected O&M Expenses Table 5 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected O&M Expenses Line Actual Projected (2) No.Account FY 24/25 (1)FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes 212 Total Employee Benefits & FICA $2,029,700 $3,085,300 $3,660,928 $4,005,225 $4,205,486 $4,415,760 9 213 214 Total Dept 901 - Pensions & Contributions $2,029,700 $3,085,300 $3,660,928 $4,005,225 $4,205,486 $4,415,760 215 216 Dept 911 - Miscellaneous 217 Prov-Compensation Adj-S Misc Charges $0 218 Workers Comp, Regular S&W $112,367 219 Workers Comp Misc Charges $132,883 220 Total Dept 911 - Miscellaneous $245,250 $275,000 $365,000 $374,125 $383,478 $393,065 221 222 Dept 912 - Replacement Reserve Account 223 Emergency Repairs $646,995 $1,000,000 $1,000,000 $1,000,000 $1,000,000 $1,000,000 10 224 Facilities Repairs $3,385,599 $2,000,000 $3,000,000 $4,000,000 $5,000,000 11 225 Total Dept 912 - Replacement Reserve Account $646,995 $4,385,599 $3,000,000 $4,000,000 $5,000,000 $6,000,000 226 227 Dept 913 - Miscellaneous 228 Provision for Training $27,683 $28,375 $29,084 $29,812 $30,557 229 Total Dept 913 - Miscellaneous $27,683 $28,375 $29,084 $29,812 $30,557 230 231 Total Fund $16,678,044 $30,052,344 $31,243,178 $33,845,520 $35,982,255 $38,166,090 232 Math check should = 0 $0 COH Wastewater Rate Model 08102026 T5 O&M Copyright 2026 All rights reserved 8/10/2026 Page 22 of 26 Appendix A - Projected O&M Expenses Table 5 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected O&M Expenses Line Actual Projected (2) No.Account FY 24/25 (1)FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes Table 5 Notes: (1) Source: FY 26/27 budget and FY 24/25 actual - revised draft FY 26/27 budget, provided by COH staff on 4/28/2026. FY 27/28 budget from draft FY 26/27 budget provided by COH staff on 4/1/2026. (2) Projected FY 26/27 expenses are based on the revised draft FY 26/27 budget (received 4/28/2026) except where noted. FY 27/28 expenses are based on the draft FY 27/28 budget except where noted. Subsequent years' projected expenses are escalated for inflation except where noted. See Table 1, Assumptions, for more detail. (3) Projected expenses in FY 28/29 and subsequent years are escalated at a 5% annual personnel rate of inflation. (4) COH intends to hire new employees needed to operate new facilities. Additional expense for 3 FTEs 3 Naalehu/Pahala 28/29) at $125K/yr per FTE are included. The anticipated 2 FTEs in Hilo and 2 FTEs in Kona are already assumed to be included in FY 27/28 budgets. (5) FY 27/28 and subsequent years escalated for the rate of general inflation and system growth. (6) The total OCE Misc Charges expense in the COH FY 26/27 and FY 27/28 budgets are not disaggregated. Past years credit card fees are used as a basis for projection. EM Admin Fees are calculated by subtracting the credit card fee expense from the total. The total OCE Misc Charge expense is based on the COH budgets for FY 26/27 and FY 27/28 with inflationary increases in subsequent years. (7) Per COH 7/25/24, this expense a portion of the Environmental Management Division administrative costs that is allocated to the Wastewater Division. It is typically added after the fiscal year ends. (8) The COH FY 26/27 draft budget was used as a basis of projection for FY 27/28 and in subsequent years. COH staff do not consider this portion of the COH draft FY 27/28 budget to be representative of future expenses. (9) Employee Benefits & FICA is projected to be 43.0% of salaries and wages expense. The 43.0% multiplier is based on actual expenses from FY 24/25. (10) Approximate historical average. (11) In 2024, COH staff provided direction to gradually increase facilities repairs to $5M per year over a five-year period. With the exception of FY 26/27, this gradual increase is retained. The FY 26/27 expense is per the draft FY 26/27 budget. COH staff increased the amount of FY 26/27 facilities repairs in order to use a portion of the accumulated fund balance. COH Wastewater Rate Model 08102026 T5 O&M Copyright 2026 All rights reserved 8/10/2026 Page 23 of 26 Appendix A - Operating Statement Table 8 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected Operating Statement Line Actual Projected No.WASTEWATER FUND SOURCES OF FUNDS FY 24/25 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes 1 Beginning of Year Balance $16,359,872 $11,212,678 $11,212,678 $11,212,678 $11,212,678 1 2 3 Wastewater Service Charge Revenues Under Existing Rates 4 Sewer Customers $15,289,158 $15,624,324 $15,780,568 $15,938,373 $16,097,757 $16,258,735 2 5 Gang Cesspool Customers $72,565 $74,024 $74,764 $75,512 $76,267 $77,029 2 6 Haulers $742,664 $757,592 $765,168 $772,819 $780,547 $788,353 2 7 8 Revenues from Projected Wastewater Service Charge Increases 3 9 Initial Year 10 Fiscal % Revenue Months 11 Year Increase of Revenue 12 FY 26/27 20.0%4 1,097,060 3,324,100 3,357,340 3,390,910 3,424,820 13 FY 27/28 20.0%4 1,329,640 4,028,810 4,069,100 4,109,790 14 FY 28/29 20.0%4 1,611,520 4,882,920 4,931,750 15 FY 29/30 18.0%4 1,757,850 5,326,290 16 FY 30/31 16.0%4 1,862,230 21 Total Revenues from Wastewater Service Charge Increases $1,097,060 $4,653,740 $8,997,670 $14,100,780 $19,654,880 22 23 Plus Over/Undercollection from Rate Design Adjustments $25,873 ($254,657)($118,317)($38,038)$23,886 4 24 25 Non-Rate Operating Revenues 26 Reimbursement for Kaloko WWTP $322,501 $322,501 $322,501 $322,501 $322,501 $322,501 2 27 Other $478,600 $0 $0 $0 $0 $0 5 28 Total Non-Rate Operating Revenues $801,101 $322,501 $322,501 $322,501 $322,501 $322,501 29 30 Non-Operating Revenues 31 Interest Income 6 32 Total Non-Operating Revenues $0 $0 $0 $0 $0 $0 33 34 General Fund Transfer $6,376,248 $3,858,869 $6,950,096 $4,702,199 $1,354,829 $0 7, 8, 9 35 36 Total Revenues $23,281,736 $21,760,242 $28,292,179 $30,690,757 $32,694,643 $37,125,384 37 38 COH Wastewater Rate Model 08102026 T8 OS Copyright 2026 All rights reserved 8/10/2026 Page 24 of 26 Appendix A - Operating Statement Table 8 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected Operating Statement 39 Actual Projected 40 WASTEWATER FUND USES OF FUNDS FY 24/25 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 Notes 41 Budgeted O&M Expenses $16,031,048 $25,666,745 $28,243,178 $29,845,520 $30,982,255 $32,166,090 10 42 Less O&M Underspend 43 Personnel ($2,074,209)($1,826,207)($1,997,955)($2,097,853)($2,202,746)11 44 Other ($1,070,699)($1,124,792)($1,156,807)($1,189,760)($1,223,678)12 45 Transfer to Equipment Replacement Fund $646,995 $1,000,000 $1,000,000 $1,000,000 $1,000,000 $1,000,000 13 46 Additional Facilities Repairs, $M $3,385,599 $2,000,000 $3,000,000 $4,000,000 $5,000,000 14 47 AOC Capital, $M $0 $0 $0 $0 $0 15 48 System Extensions, $M $0 $0 $0 $0 $0 15 49 50 Total Uses of Funds $16,678,044 $26,907,436 $28,292,179 $30,690,757 $32,694,643 $34,739,666 51 52 End of Year Balance, Sewer Fund $11,212,678 $11,212,678 $11,212,678 $11,212,678 $13,598,396 16, 17 As of 2026, the General Fund pays for all of the wastewater utility's debt service. In the future, wastewater rates revenues are projected to exceed O&M/replacement expenses. COH could choose to use these funds to pay for some of its own debt service and/or capital expenses. COH Wastewater Rate Model 08102026 T8 OS Copyright 2026 All rights reserved 8/10/2026 Page 25 of 26 Appendix A - Operating Statement Table 8 County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Projected Operating Statement Notes:(1) Wastewater Fund balance as of 6/30/2025, obtained from COH staff, 2/4/2026. (2) See Table 4a, Projected Revenues Under Existing Rate Schedule, for more detail. (3) The initial year months of revenue incorporates a two-month billing lag between the effective date of the rate increase and when the County receives revenues resulting from the rate increase. (4) See Table COS-11 (Backcalculation of Revenues Under Proposed Wastewater Service Charges, line 32 for more detail. The rate design adjustments collect less revenue than calculated by the percentage increases in Lines 12 through 20. (5) This revenue is a non-recurring insurance reimbursement that occurred in FY 24/25. (6) Interest income on the Fund Balance in the Wastewater Fund is not considered in this Rate Study. Interest Income is returned to the General Fund in consideration of the ongoing General Fund support of the Wastewater Utility. (7) FY 24/25 actuals from the Revenue Summary associated with the draft FY 26/27 budget. FY 26/27: revised draft FY 26/27 budget. Source: COH staff, 4/28/2026. (8) FY 27/28 and subsequent years General Fund Transfer is calculated as the difference between revenues and expenses. In past years, actual O&M expenses have been less than budgeted O&M expenses. Even with the underspend assumptions built in to this analysis (See Table 5, Projected O&M Expenses), the projected General Fund Transfers shown in this report may be overstated. (9) The General Fund Transfer is projected to be reduced to $0 by FY 30/31. At that time, the Fund Balance in the Sewer Fund would increase. The General Fund Transfer may reach $0 earlier than shown in this Table if actual O&M expenses are less than projected. (10) See Table 5, Projected O&M Expenses, for more detail. (11) 15% underspend on personnel expenses including pensions and contributions is projected throughout this Rate Study starting FY 27/28. FY 26/27 uses a 20% underspend on personnel expenses. (12) 7% underspend on all non-personnel O&M expenses is projected throughout this Rate Study. (13) Approximate historical average. (14) In 2024, COH staff provided direction to gradually increase facilities repairs to $5M per year over a five-year period. With the exception of FY 26/27, this gradual increase is retained. The FY 26/27 expense is per the draft FY 26/27 budget. COH staff increased the amount of FY 26/27 facilities repairs in order to use a portion of the accumulated fund balance. (15) AOC capital and system extensions are not considered in this Rate Study because rate revenues are not projected to be sufficient to fund them. AOC capital and system extension funding will be considered in the forthcoming COH long-range financial plan. (16) The projected ending FY 26/27 Sewer Fund balance is calculated by adding the beginning year fund balance, revenues, and the General Fund transfer, and then subtracting expenses. (17) In FY 27/28 and subsequent years for the purposes of this Rate Study, the Fund Balance is projected to remain constant as long as the General Fund Transfer is greater than $0. The Fund Balance is projected to increase only when Wastewater Service Charge revenues are sufficient to pay for O&M expenses, the transfer to the Emergency Replacement Fund, and the Additional Facilities Repairs. COH Wastewater Rate Model 08102026 T8 OS Copyright 2026 All rights reserved 8/10/2026 Page 26 of 26 Wastewater Rate Study – County of Hawai’i, Wastewater Division B-1 County of HAWAII Wastewater Rate Study Report 08102026 A Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-1: Cost-of-Service Analysis - Functionalization of Projected FY 26/27 O&M Expenses Projected Total $ Line FY 26/27 (1) Treatment Collection Customer Direct- Pvt Haulers Direct- Gang Cess Direct- PreTreat Admin Note 1 Total Regular S&W $6,934,634 $4,379,474 $2,229,967 $29,865 $149,824 $0 $115,639 $29,865 2 2 Total Overtime S&W 140,309 88,610 45,119 604 3,031 0 2,340 604 2 3 Total Miscellaneous S&W 210,800 133,128 67,787 908 4,554 0 3,515 908 2 4 Less Personnel Underspend (2,074,209)(1,309,938)(667,002)(8,933)(44,814)0 (34,589)(8,933)2 5 Total OCE Postage & Freight 46,000 0 4,600 36,800 0 0 0 4,600 3 6 Total OCE Telephone 66,000 41,681 21,224 284 1,426 0 1,101 284 2 7 Total OCE Janitorial 90,000 0 0 0 0 0 0 90,000 8 Total OCE Travel/Conference 42,000 0 0 0 0 0 0 42,000 9 Total OCE Printing 21,100 0 0 18,990 0 0 0 2,110 10 Total OCE Advertising - Public Notices 10,000 0 0 0 0 0 0 10,000 11 Total Wastewater OCE Equip Repairs/Maint 334,100 167,050 167,050 0 0 0 0 0 4 12 Total OCE Repairs to Facilities 920,000 0 0 0 0 0 0 920,000 13 Total OCE Rental/Lease of Equip 585,491 146,373 439,118 0 0 0 0 0 14 Total OCE Mileage & Auto Allowance 2,300 0 0 0 0 0 0 2,300 15 Total OCE Water, Gas and Sewer 178,530 178,530 0 0 0 0 0 0 16 Total OCE Electricity 3,660,168 2,876,892 783,276 0 0 0 0 0 5 17 Total OCE Misc. Contract Services 1,039,560 575,648 143,912 0 20,000 0 300,000 0 6 18 Total OCE Refuse Disposal 830,000 79,680 0 0 0 0 0 750,320 7 19 Total OCE Agricultural Supplies 6,000 0 0 0 0 0 0 6,000 20 Total OCE Cleaning/Sanitation Supplies 938,500 931,650 0 0 0 6,850 0 0 8 21 Total OCE Fuels & Lubricants 137,500 86,836 44,216 592 2,971 0 2,293 592 2 22 Total OCE Computer & Office Supp 24,700 12,350 6,175 0 0 0 0 6,175 3 23 Total OCE M.V./Hvy Eqpt Parts/Supp 542,200 487,980 54,220 0 0 0 0 0 9 24 Total OCE Misc. Materials & Supp 373,400 186,700 186,700 0 0 0 0 0 9 25 Total Wastewater OCE Subscrip & Membership 168,424 0 0 0 0 0 0 168,424 26 Total OCE, Building Rent 135,000 0 0 0 0 0 0 135,000 27 Total OCE Misc. Charges 1,176,446 0 0 55,000 0 0 0 1,121,446 10 28 Wastewater Eqpt, Motor Vehicle 640,000 404,183 205,804 2,756 13,827 0 10,672 2,756 2 29 Wastewater Eqpt, Computer Eqpt & Software 8,500 0 0 0 0 0 0 8,500 30 Total Computer Equip & Software 22,100 13,957 7,107 95 477 0 369 95 2 31 Total Misc. Equipment 2,995,000 898,500 2,096,500 0 0 0 0 0 9 32 Total Operator Training Facility 0 0 0 0 0 0 0 0 2 33 Total Employee Benefits & FICA 3,085,300 1,948,479 992,138 13,287 66,658 0 51,449 13,287 2 34 Total Dept 911 - Miscellaneous 275,000 173,673 88,432 1,184 5,941 0 4,586 1,184 235Total Dept 913 - Miscellaneous 27,683 17,483 8,902 119 598 0 462 119 2 36 Less Other O&M Underspend (1,070,699)(509,542)(298,006)(8,107)(3,167)(480)(22,364)(229,033)11 37 Total O&M $22,521,837 $12,009,377 $6,627,238 $143,446 $221,329 $6,371 $435,472 $3,078,605 38 Math Check = OS TRUE COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 1 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-1 (Continued): Cost-of-Service Analysis - Functionalization of Projected FY 26/27 O&M Expenses FY 26/27 Percentage Line Projected (1) Treatment Collection Customer Direct- Pvt Haulers Direct- Gang Cess Direct- PreTreat Admin Note 1 Total Regular S&W $6,934,634 63.2%32.2%0.4%2.2%1.7%0.4%2 2 Total Overtime S&W $140,309 63.2%32.2%0.4%2.2%1.7%0.4%2 3 Total Miscellaneous S&W $210,800 63.2%32.2%0.4%2.2%1.7%0.4%2 4 Less Personnel Underspend ($2,074,209)63.2%32.2%0.4%2.2%1.7%0.4%2 5 Total OCE Postage & Freight $46,000 0.0%10.0%80.0%10.0%3 6 Total OCE Telephone $66,000 63.2%32.2%0.4%2.2%1.7%0.4%2 7 Total OCE Janitorial $90,000 0.0%0.0%0.0%100.0%8 Total OCE Travel/Conference $42,000 0.0%0.0%0.0%100.0% 9 Total OCE Printing $21,100 0.0%0.0%90.0%10.0% 10 Total OCE Advertising - Public Notices $10,000 0.0%0.0%0.0%100.0% 11 Total Wastewater OCE Equip Repairs/Maint $334,100 50.0%50.0%0.0%0.0%4 12 Total OCE Repairs to Facilities $920,000 0.0%0.0%0.0%100.0% 13 Total OCE Rental/Lease of Equip $585,491 25.0%75.0%0.0%0.0% 14 Total OCE Mileage & Auto Allowance $2,300 0.0%0.0%0.0%100.0% 15 Total OCE Water, Gas and Sewer $178,530 100.0%0.0%0.0%0.0% 16 Total OCE Electricity $3,660,168 78.6%21.4%0.0%0.0%5 17 Total OCE Misc. Contract Services $1,039,560 55.4%13.8%0.0%1.9%28.9%0.0%6 18 Total OCE Refuse Disposal $830,000 9.6%0.0%0.0%90.4%7 19 Total OCE Agricultural Supplies $6,000 0.0%0.0%0.0%100.0% 20 Total OCE Cleaning/Sanitation Supplies $938,500 99.3%0.0%0.0%0.7%0.0%8 21 Total OCE Fuels & Lubricants $137,500 63.2%32.2%0.4%2.2%1.7%0.4%2 22 Total OCE Computer & Office Supp $24,700 50.0%25.0%0.0%25.0%3 23 Total OCE M.V./Hvy Eqpt Parts/Supp $542,200 90.0%10.0%0.0%0.0%9 24 Total OCE Misc. Materials & Supp $373,400 50.0%50.0%0.0%0.0%9 25 Total Wastewater OCE Subscrip & Membership $168,424 0.0%0.0%0.0%100.0% 26 Total OCE, Building Rent $135,000 0.0%0.0%0.0%100.0% 27 Total OCE Misc. Charges $1,176,446 0.0%0.0%4.7%95.3%10 28 Wastewater Eqpt, Motor Vehicle $640,000 63.2%32.2%0.4%2.2%1.7%0.4%2 29 Wastewater Eqpt, Computer Eqpt & Software $8,500 0.0%0.0%0.0%100.0% 30 Total Computer Equip & Software $22,100 63.2%32.2%0.4%2.2%1.7%0.4%2 31 Total Misc. Equipment $2,995,000 30.0%70.0%0.0%0.0%9 32 Total Operator Training Facility $0 63.2%32.2%0.4%2.2%1.7%0.4%233Total Employee Benefits & FICA $3,085,300 63.2%32.2%0.4%2.2%1.7%0.4%2 34 Total Dept 911 - Miscellaneous $275,000 63.2%32.2%0.4%2.2%1.7%0.4%2 35 Total Dept 913 - Miscellaneous $27,683 63.2%32.2%0.4%2.2%1.7%0.4%2 36 Less Other O&M Underspend ($1,070,699)47.6%27.8%0.8%0.3%0.0%2.1%21.4%11 37 Total O&M $22,521,837 53.3%29.4%0.6%1.0%0.0%1.9%13.7% COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 2 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-1 Notes: (1) See Table 5, Projected O&M Expenses, for more detail. (2) Based on functionalization of labor costs for COH Wastewater Division employees. (3) Functionalization percentages were developed for the 2018 Rate Study and retained for this 2026 Rate Study. Postage expenses are primarily for billing and customer information. (4) 50/50 split between treatment and collection based on review of FY 24/25 budget with the majority of expenses split between "line equipment" and "plant equipment" (5) Based on review of COH HELCO bills from November 2022 through October 2023 (6) $20K for sampling directly assigned to private haulers, per COH staff 5/1/2025. $300K directly assigned to non-residential customers for pre-treatment program expenses, confirmed by COH staff 5/5/2025 to be recurring. Remainder of expense assigned 80/20 treatment vs. collection based on review of budgetary line items. (7) 80K of 830K (rounds to 9.6%) is solid waste division refuse hauling from wastewater facilities. Charge to admin. The remainder is tipping fees for biosolids. (8) Functionalized amount to gang cesspools is based on the average cost of sodium hydroxide used for gang cesspools over the past two years, per COH staff, 5/5/2025. (9) Based on review of draft FY 26/27 budgeted expenses included in this category. (10) $55K budgeted for credit card fees is functionalized to customer, the balance is for (11) Weighted average of all other non-labor O&M expenses. Table COS-2: Cost-of-Service Analysis - Allocation of Rate Revenue Requirement FY 26/27 Total $ Line 12 month total Flow BOD TSS Direct- Pvt Haulers Direct- Gang Cess Direct- PreTreat Customer Notes 1 Component of Rate Revenue Requirement 2 Debt Service $0 $0 $0 $0 $0 $0 $0 $0 1 3 O&M Expenses 4 Treatment 12,009,377 4,003,126 4,003,126 4,003,126 0 0 0 0 5 Collection 6,627,238 5,964,514 0 0 0 0 0 662,724 6 Direct - Private Haulers 221,329 0 0 0 221,329 0 0 0 7 Direct - Gang Cesspools 6,371 0 0 0 0 6,371 0 0 8 Direct - Pre-Treatment 435,472 0 0 0 0 0 435,472 0 9 Customer 143,446 0 0 0 0 0 0 143,446 10 Administrative 3,078,605 1,822,096 532,035 532,035 28,987 834 57,033 105,583 2 11 Equipment Replacement Fund 1,000,000 666,667 166,667 166,667 0 0 0 0 3 12 Additional Facilities Repairs, $M 3,385,599 3,385,599 0 0 0 0 0 0 4 13 Less Reimbursement for Kaloko WWTP (322,501)(107,500)(107,500)(107,500)0 0 0 0 5 14 AOC Capital and System Extensions, $M 0 0 0 0 0 0 0 0 1 15 Less Transfer from General Fund (3,884,742)(2,299,215)(671,349)(671,349)(36,578)(1,053)(71,968)(133,231)2 14 Change in Fund Balance (5,147,194)(3,046,407)(889,522)(889,522)(48,464)(1,395)(95,356)(176,527)2 15 Total $17,553,000 $10,388,880 $3,033,456 $3,033,456 $165,274 $4,757 $325,182 $601,995 16 Check: total = sum of allocations TRUE 17 Check: Total + GF Transfer = OS Total Exp TRUE Excludes consideration of overcollecting rates due to adjustments from COS rates 18 Check: O&M Expenses COS1=COS2 TRUE COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 3 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-2 (continued): Cost-of-Service Analysis - Allocation of Rate Revenue Requirement FY 26/27 Percentage Line 12 month total Flow BOD TSS Direct- Pvt Haulers Direct- Gang Cess Direct- PreTreat Customer Notes 1 Component of Rate Revenue Requirement 2 Debt Service $0 1 3 O&M Expenses 4 Treatment 12,009,377 33.3%33.3%33.3%0.0% 5 Collection 6,627,238 90.0%10.0% 6 Direct - Private Haulers 221,329 100.0% 7 Direct - Gang Cesspools 6,371 100.0%8 Direct - Pre-Treatment 435,472 100.0% 9 Customer 143,446 100% 10 Administrative 3,078,605 59.2%17.3%17.3%0.9%0.0%1.9%3.4%2 11 Equipment Replacement Fund 1,000,000 66.7%16.7%16.7%0.0%3 12 Additional Facilities Repairs, $M 3,385,599 100.0%4 13 Less Reimbursement for Kaloko WWTP (322,501)33.3%33.3%33.3%0.0%5 14 AOC Capital and System Extensions, $M 0 1 15 Less Transfer from General Fund (3,884,742)59.2%17.3%17.3%0.9%0.0%1.9%3.4%2 16 Change in Fund Balance (5,147,194)59.2%17.3%17.3%0.9%0.0%1.9%3.4%2 17 Total $17,553,000 59.2%17.3%17.3%0.9%0.0%1.9%3.4% Notes: (1) Allocation factors not developed for these items because no costs associated with these items are funded from wastewater rates. (2) Allocated based on weighted average of other rate revenue requirement items. (3) Based on 50/50 split of costs to collection and treatment in Table COS-1, and allocation of all collection to flow and allocation of treatment split equally between flow, BOD, and TSS. (4) Allocated entirely to flow because these are entirely major collection system repairs. (5) Allocated in the same manner as treatment O&M expenses. COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 4 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-3: Cost-of-Service Analysis - Distribution of Rate Revenue Requirement Direct - Direct - Direct - Line Flow BOD TSS Customer Private Haulers Gang Cesspools Pre- Treatment Total Notes Math Check 1 Rate Revenue Requirement 2 Full Year FY 26/27 $10,388,880 $3,033,456 $3,033,456 $601,995 $165,274 $4,757 $325,182 $17,553,000 TRUE 3 4 Per Month for Calendar Year 2027, the time period where the rate increase will be effect and revenues will be received 1 5 Four Months in FY 26/27 $973,957 $284,386 $284,386 $56,437 $15,494 $446 $30,486 $1,645,593 TRUE 6 7 Projected FY 26/27 Units of Service, per Month 8 Amount 147,123 253,742 248,831 6,162 9 Units kgal lbs lbs customers 10 Math Check, Sum of Below TRUE TRUE TRUE TRUE 11 Math Check, Source Data TRUE TRUE TRUE 12 13 Unit Cost-of-Service, $/unit $/kgal $/lb BOD $/lb TSS $/customer/mo. 14 Unadjusted 6.62 1.12 1.14 9.16 15 Adjusted 16 Gang Cesspools 3.33 0.00 0.00 9.16 17 Private Haulers 3.33 1.13 1.15 9.16 18 All Other Customers 6.67 1.13 1.15 9.16 19 Note Reference Note 2 Note 3 Note 3 Note 4 Note 5 20 21 Distribution of Monthly Allocated Revenue Requirement to Customer Classes 22 Single-Unit Residential 23 Per Month Units of Service 30,094 49,721 35,408 4,609 24 Percentage of Service 20%20%14%75% 25 Unadjusted Per-Month Cost of Service $200,613 $56,299 $40,768 $42,213 $339,894 26 27 Multi-Unit Residential 28 Per Month Units of Service 54,312 89,734 63,901 276 29 Percentage of Service 37%35%26%4% 30 Unadjusted Per-Month Cost of Service $362,055 $101,606 $73,576 $2,528 $539,765 31 32 Gang Cesspools33Per Month Units of Service 1,564 2,583 1,840 252 34 Percentage of Service 1%1%1%4% 35 Unadjusted Per-Month Cost of Service $5,212 $0 $0 $2,308 $446 $7,966 COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 5 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-3 (continued): Cost-of-Service Analysis - Distribution of Rate Revenue Requirement 36 Non-Residential 37 Per Month Units of Service 50,775 83,890 55,604 1,004 38 Percentage of Service 35%33%22%16% 39 Unadjusted Per-Month Cost of Service $338,475 $94,988 $64,023 $9,196 $30,486 $537,168 40 41 Hotels 42 Per Month Units of Service 9,904 25,620 11,653 21 43 Percentage of Service 7%10%5%0% 44 Unadjusted Per-Month Cost of Service $66,024 $29,010 $13,417 $192 $108,643 45 46 Private Haulers (Septage) 47 Per Month Units of Service 288 1,061 53,923 48 Percentage of Service 0%0%22%0% 49 Unadjusted Per-Month Cost of Service $961 $1,202 $62,087 $0 $9,438 $73,688 50 51 Private Haulers (Cesspool) 52 Per Month Units of Service 44 161 8,164 53 Percentage of Service 0%0%3%0% 54 Unadjusted Per-Month Cost of Service $146 $182 $9,400 $0 $1,429 $11,157 55 56 Private Haulers (Portable Toilets) 57 Per Month Units of Service 55 289 6,463 58 Percentage of Service 0%0%3%0% 59 Unadjusted Per-Month Cost of Service $184 $327 $7,442 $0 $1,805 $9,757 60 61 Private Haulers (WWTP Activated Sludge) 62 Per Month Units of Service 86 683 11,875 63 Percentage of Service 0%0%5%0% 64 Unadjusted Per-Month Cost of Service $287 $773 $13,673 $0 $2,822 $17,556 65 66 Units of Service Math Check: = Total?TRUE TRUE TRUE TRUE 67 % of Service Math Check: = 100%?TRUE TRUE TRUE TRUE 68 $ Math Check: = Total?TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 6 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-3 Notes: (1) The 1/1/2027 rate increase will be in effect until 1/1/2028. With a two-month billing lag, the rate design is based on the Rate Revenues collected for Calendar Year 2027. The total in this row is the projected FY 26/27 revenue from existing rates divided by 12, plus the projected FY 26/27 revenue from the 1/1/2027 proposed rate increase divided by 4. (2) Adjustments to the distribution of the Flow unit cost of service: The flow allocation in Table COS-2 for the collection system and the treatment plant is approximately equal. 1.Gang cesspools: do not use the treatment plant, so they are not charged the treatment component of flow expenses. 2.Private Haulers: private haulers do not use the collection system, so they are not charged the collection system component of flow expenses. (3) Adjustments to the distribution of the BOD and TSS unit costs of service: 1.Gang cesspools do not use the treatment plants, so no BOD and TSS costs are distributed to the gang cesspool customer class. (4) Direct assigned costs to haulers are distributed among each class of private hauler proportional to their relative amount of flow. (5) Direct assigned pre-treatment costs are distributed among non-residential customers proportional to BOD loading. COH staff confirmed (5/5/2025) that there are no residential or hotel Significant Industrial Users. COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 7 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-4: Cost-of-Service Based Rate Design Calculations Line 1 Combined Single-Unit and Multi-Unit Residential 2 Monthly Base Rate Charge per Unit 3 Per Month Rate Revenue Requirement $879,659 Value from Table COS-3 4 Units of Service 13,603 Note 1 5 Monthly Base Rate Charge per Unit $64.67 Rounded to nearest $0.01 6 7 Gang Cesspools 8 Monthly Base Rate Charge per Unit 9 Per Month Rate Revenue Requirement $7,965.82 Value from Table COS-3 10 Units of Service 252 Note 1 11 Monthly Base Rate Charge per Unit $31.61 Rounded to nearest $0.01 12 13 Non-Residential 14 Monthly Base Rate Charge per Unit 15 Customer Component 16 Per Month Customer Allocation $9,196 Value from Table COS-3 (Customer-Allocated Component Only) 17 Units of Service 1,410 Note 1 18 Subtotal, Customer Component $6.52 19 20 Volume Component for the 8,000 gallons/month Included in the Monthly Base Rate Charge 21 Cost-of-Service Usage Charge, $/kgal $9.02 See calculation in Line 33 below. 22 kgal Included in Monthly Base Rate Charge 8 23 Volume Component, $/month $72.15 24 25 Monthly Base Rate Charge per Unit $78.67 Note 2. Rounded to nearest $0.01 26 27 Uniform Block Usage Charge Calculation Formula is Derived as Follows: 28 Monthly Non-Residential Revenue Requirement = Billing Units * (Customer Component + 8 * Usage Charge) + Usage Charge * (Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 29 Monthly Non-Residential Revenue Requirement = Billing Units * Customer Component + Billing Units * 8 * Usage Charge + Usage Charge * (Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 30 Monthly Non-Residential Revenue Requirement - Billing Units * Customer Component = Billing Units * 8 * Usage Charge + Usage Charge * (Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 31 Monthly Non-Residential Revenue Requirement - Billing Units * Customer Component = Usage Charge * (Billing Units * 8 + Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 32 Usage Charge = (Monthly Non-Residential Revenue Requirement - Billing Units * Customer Component) / (Billing Units * 8 + Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 33 Uniform Block Usage Charge =$9.02 $/kgal COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 8 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-4 (Continued): Cost-of-Service Based Rate Design Calculations 34 Hotels 35 Monthly Base Rate Charge 36 Customer Component 37 Per Month Customer Allocation $192 Value from Table COS-3 (Customer-Allocated Component Only) 38 Units of Service 21 Note 1 39 Subtotal, Customer Component $9.16 40 Volume Component for the 8,000 gallons/month Included in the Monthly Base Rate Charge 41 Uniform Block Cost-of-Service Usage Charge, $/kgal $10.82 See calculation in Line 53 below. 42 kgal Included in Monthly Base Rate Charge 8 Note 1 43 Volume Component, $/month $86.56 44 45 Monthly Base Rate Charge per Unit $95.72 Note 2. Rounded to nearest $0.01 46 47 Uniform Block Usage Charge Calculation Formula is Derived as Follows: 48 Monthly Hotel Revenue Requirement = Billing Units * (Customer Component + 8 * Usage Charge) + Usage Charge * (Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 49 Monthly Hotel Revenue Requirement = Billing Units * Customer Component + Billing Units * 8 * Usage Charge + Usage Charge * (Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 50 Monthly Hotel Revenue Requirement - Billing Units * Customer Component = Billing Units * 8 * Usage Charge + Usage Charge * (Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 51 Monthly Hotel Revenue Requirement - Billing Units * Customer Component = Usage Charge * (Billing Units * 8 + Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 52 Usage Charge = (Monthly Hotel Revenue Requirement - Billing Units * Customer Component) / (Billing Units * 8 + Tier 2 kgal/month + Tier 3 kgal/month + Tier 4 kgal/month) 53 Uniform Block Usage Charge =$10.82 $/kgal 54 55 Private Haulers, Septage and Cesspool 56 Discharge Fee per 500 Gallons 57 Per Month Rate Revenue Requirement $84,844.99 Value from Table COS-3 58 Units of Service 664 units of 500 gallons 59 Discharge Fee, $/500 gallons $127.75 60 61 Private Haulers, Portable Toilets 62 Discharge Fee per 500 Gallons 63 Per Month Rate Revenue Requirement $9,757.36 Value from Table COS-3 64 Units of Service 110 units of 500 gallons 65 Discharge Fee, $/500 gallons $88.44 66 67 Private Haulers, WWTP 68 Discharge Fee per 500 Gallons 69 Per Month Rate Revenue Requirement $17,555.76 Value from Table COS-3 70 Units of Service 173 units of 500 gallons 71 Discharge Fee, $/500 gallons $101.77 COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 9 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-4 (Continued): Cost-of-Service Based Rate Design Calculations 72 Non-Residential and Hotel Tiered Usage Charge Calculation 73 74 Policy Decision per County Council's adoption of 2019 rate increases. 75 The difference in the Usage Charge between Tier 2 and Tier 3 = $1.50. This is the difference in the current Usage Charges, effective 4/1/2023. 76 The difference in the Usage Charge between Tier 3 and Tier 4 = $0.50. This is the difference in the current Usage Charges, effective 4/1/2023. 77 78 Projected FY 26/27 Sales by Tier, kgal/year 79 Non-Residential FY 26/27 80 Excluding Tiered Usage Charge, $/kgal Math Check: Non-Residential 81 Hotels Hotels Hotels Non-Res Tier Calcs = Revenue Neutral? 82 Tier 83 0 - 8 kgal 1,228 42,181 $0.00 $0.00 84 8 - 15 kgal 1,048 27,363 $8.85 $7.15 $1.86 $51,023.42 85 15 - 30 kgal 2,076 44,026 $10.35 $8.65 $0.36 $16,055.70 86 >30 kgal 115,134 495,732 $10.85 $9.15 ($0.14)($67,079.12) 87 Total 119,486 609,302 $0.00 88 89 Formula Derivation, where x = Tier 2 $/kgal: 90 Tier 2 kgal * x + Tier 3 kgal * ( x + 1.5) + Tier 4 kgal * ( x +2) = Average $/kgal* ( Tier 2 kgal + Tier 3 kgal + Tier 4 kgal) 91 (Tier 2 kgal + Tier 3 kgal + Tier 4 kgal) * x + Tier 3 kgal*1.5 + Tier 4 kgal*2 = Average $/kgal * (Tier 2 kgal + Tier 3 kgal + Tier 4 kgal) 92 (Tier 2 kgal + Tier 3 kgal + Tier 4 kgal) * x = Average $/kgal * ( Tier 2 kgal + Tier 3 kgal + Tier 4 kgal) - Tier 3 kgal*1.5 - Tier 4 kgal*2 93 x = [Average $/kgal * (Tier 2 kgal + Tier 3 kgal + Tier 4 kgal) - Tier 3 kgal*1.5 - Tier 4 kgal*2] / (Tier 2 kgal + Tier 3 kgal + Tier 4 kgal) 94 Notes: (1) The number of customers is used to determine the Revenue Requirement for each customer class in Table COS-3 because the number of customers is what determines the cost to provide the customer-allocated services. The number of billing units is used in rate design calculations, because the number of billing units is how costs are recovered. For example, a 10 unit apartment complex will receive one bill for all 10 billing units. (2) Rounded to nearest $0.01. Equals Customer Component plus 8 times the Volume Component. This Monthly Base Rate Charge includes first 8,000 gallons/month COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 10 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-5: Cost-of-Service Wastewater Service Charges (Before Rounding and Adjustments) Existing Rates Cost-of-Service Wastewater Service Charges Line Customer Class 1/1/2025 1/1/2026 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 Units 1 Single-Unit Residential $52.00 $52.00 $64.67 $77.60 $93.12 $109.89 $127.47 $/Unit 2 Multi-Unit Residential $52.00 $52.00 $64.67 $77.60 $93.12 $109.89 $127.47 $/Unit 3 Gang Cesspools, Monthly Charge per Unit $25.00 $25.00 $31.61 $37.93 $45.52 $53.71 $62.31 $/Unit 4 5 Non-Residential 6 Monthly Base Rate Charge per Unit $54.00 $54.00 $78.67 $94.40 $113.28 $133.68 $155.06 $/Unit 7 Monthly Usage Charge per 1,000 Gallons 8 0 - 8 kgal $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $/kgal 9 8 - 15 kgal $7.50 $7.50 $7.15 $8.59 $10.30 $12.16 $14.10 $/kgal 10 15 - 30 kgal $9.00 $9.00 $8.65 $10.39 $12.46 $14.71 $17.06 $/kgal 11 >30 kgal $9.50 $9.50 $9.15 $10.99 $13.18 $15.55 $18.04 $/kgal 12 13 Hotels 14 Monthly Base Rate Charge $54.00 $54.00 $95.72 $114.86 $137.84 $162.65 $188.67 $/Unit 15 Monthly Usage Charge per 1,000 Gallons 16 0 - 8 kgal $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $/kgal 17 8 - 15 kgal $7.50 $7.50 $8.85 $10.62 $12.74 $15.03 $17.44 $/kgal 18 15 - 30 kgal $9.00 $9.00 $10.35 $12.42 $14.90 $17.58 $20.39 $/kgal 19 >30 kgal $9.50 $9.50 $10.85 $13.02 $15.62 $18.43 $21.38 $/kgal 20 21 Private Haulers, $ per 500 Gallons 22 Septage $64.00 $64.00 $127.75 $153.30 $183.96 $217.07 $251.80 $/500 gal 23 Cesspool $64.00 $64.00 $127.75 $153.30 $183.96 $217.07 $251.80 $/500 gal 24 Portable Toilets $64.00 $64.00 $88.44 $106.12 $127.35 $150.27 $174.31 $/500 gal 25 WWTP $64.00 $64.00 $101.77 $122.13 $146.55 $172.93 $200.60 $/500 gal COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 11 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-6: Backcalculation of Revenues Under Cost-of-Service Rates Projected Rate Revenues Line Customer Class FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 1 Single-Unit Residential $3,272,198 $4,055,275 $4,915,003 $5,919,184 $7,008,768 2 Multi-Unit Residential $5,905,474 $7,318,368 $8,870,448 $10,684,618 $12,653,562 3 Gang Cesspools $82,263 $102,770 $124,781 $150,538 $178,555 4 5 Non-Residential 6 Monthly Base Rate Charge $1,052,819 $1,433,934 $1,737,638 $2,092,307 $2,477,050 7 Monthly Usage Charge 8 0 - 8 kgal $0 $0 $0 $0 $0 9 8 - 15 kgal $202,069 $210,905 $255,613 $307,866 $364,595 10 15 - 30 kgal $391,161 $410,477 $497,502 $599,215 $709,659 11 >30 kgal $4,652,329 $4,889,021 $5,925,495 $7,136,801 $8,452,136 12 13 Hotels 14 Monthly Base Rate Charge $17,112 $25,730 $30,875 $36,819 $43,173 15 Monthly Usage Charge 16 0 - 8 kgal 17 8 - 15 kgal $8,331 $9,984 $12,094 $14,557 $17,228 18 15 - 30 kgal $19,616 $23,133 $28,038 $33,782 $40,020 19 >30 kgal $1,145,463 $1,345,416 $1,630,646 $1,963,983 $2,325,950 20 21 Private Haulers 22 Septage $590,093 $952,751 $1,154,747 $1,390,685 $1,647,150 23 Cesspool $89,341 $144,166 $174,635 $210,202 $248,764 24 Portable Toilets $95,520 $126,215 $153,043 $184,393 $218,431 25 WWTP $158,543 $226,885 $274,867 $331,197 $392,362 26 27 Total $17,682,331 $21,275,029 $25,785,424 $31,056,147 $36,777,403 28 Revenue Requirement $17,553,000 $21,274,239 $25,784,374 $31,055,351 $36,778,997 29 Delta, >0 = overcollect $129,332 $790 $1,050 $796 ($1,593) COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 12 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-7: Adjustments to Cost-of-Service Based Rates Adjustment 1: Non-Residential Usage Charges Don't Change on 1/1/2027. Additional Revenues Used to Offset Residential Rates Methodology: the residential rate offset is selected to make the 10-year effect of Adjustment 1 approximately revenue-neutral. Because of the mid-year rate increases and calculation of revenues and expenses on a fiscal year basis, the residential rate offset can't be calculated. If value in Line 27 is >$0, then the additional revenue from non-residential rates is greater than the lost revenue from the residential revenue offset. Existing Projected Line 1/1/2025 1/1/2026 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 1 Non-Residential Usage Charges 2 Cost-of-Service Based Usage Charges, $/kgal 3 0 - 8 kgal $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 4 8 - 15 kgal $7.50 $7.50 $7.15 $8.59 $10.30 $12.16 $14.10 5 15 - 30 kgal $9.00 $9.00 $8.65 $10.39 $12.46 $14.71 $17.06 6 >30 kgal $9.50 $9.50 $9.15 $10.99 $13.18 $15.55 $18.04 7 8 Adjusted Usage Charges 9 0 - 8 kgal $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 10 8 - 15 kgal $7.50 $7.50 $7.50 $9.00 $10.80 $12.74 $14.78 11 15 - 30 kgal $9.00 $9.00 $9.00 $10.80 $12.96 $15.29 $17.74 12 >30 kgal $9.50 $9.50 $9.50 $11.40 $13.68 $16.14 $18.73 13 14 Additional Revenue from Adjustment 1 15 0 - 8 kgal $0 $0 $0 $0 $0 $0 16 8 - 15 kgal 0 3,153 10,191 12,351 14,876 17,617 17 15 - 30 kgal 0 5,073 16,397 19,873 23,936 28,348 18 >30 kgal 0 57,125 184,627 223,768 269,512 319,184 19 Total $0 $65,351 $211,215 $255,993 $308,324 $365,149 20 21 22 Residential Rate Offset Calculation FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 23 Reduction in Residential Rate Corresponding to Adjustment 1, $/month/Unit ($1.20)($1.50)($1.70)($2.00)($2.00) 24 Billing Units 13,603 13,740 13,878 14,017 14,156 25 Revenue Difference from Reducing Residential Rate ($65,294)($214,344)($260,906)($302,767)($339,744) 26 27 Check: Undercollect if <$0. See methodology note.$57 ($3,129)($4,914)$5,557 $25,405 COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 13 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-7 (Continued): Adjustments to Cost-of-Service Based Rates Adjustment 2: Private Hauler Rate Adjustments Methodology: Phase in Rate Increases for Private Hauler Customer Classes Net Increase in revenues from these adjustments is not distributed among other customers. The result is that additional sewer system revenue is collected. Existing Projected Line 1/1/2025 1/1/2026 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 Units 28 Private Haulers - WWTP 29 Cost-of-Service Rate $64.00 $64.00 $101.77 $122.13 $146.55 $172.93 $200.60 $/500 gal 30 Proposed Rate $64.00 $64.00 $95.00 $125.00 $155.00 $172.93 $200.60 $/500 gal 31 Projected Disposal Quantity, kgal/year 1,025 1,035 1,045 1,055 1,066 1,077 kgal/year 32 Additional Revenue, $/Year $0 ($4,673)($7,435)$9,983 $12,007 $0 33 34 Private Haulers - Septage and Cesspool 35 Cost-of-Service Rate $64.00 $64.00 $127.75 $153.30 $183.96 $217.07 $251.80 $/500 gal 36 Proposed Rate $64.00 $64.00 $100.00 $140.00 $180.00 $217.07 $251.80 $/500 gal 37 Projected Disposal Quantity, kgal/year 3,946 3,985 4,025 4,065 4,105 4,146 kgal/year 38 Additional Revenue, $/Year $0 ($73,713)($184,584)($82,782)($21,647)$0 39 40 Private Haulers - Portable Toilets 41 Cost-of-Service Rate $64.00 $64.00 $88.44 $106.12 $127.35 $150.27 $174.31 $/500 gal 42 Proposed Rate $64.00 $64.00 $84.00 $104.00 $127.00 $150.27 $174.31 $/500 gal 43 Projected Disposal Quantity, kgal/year 655 662 669 676 683 690 kgal/year 44 Additional Revenue, $/Year $0 ($1,957)($4,903)($2,069)($316)$0 45 46 Total Change in Revenue 47 $/Year (>$0 = overcollect)$0 ($80,344)($196,921)($74,868)($9,956)$0 48 % Adjustment to Non-Haulers Rates 0.0%0.0%0.0%0.0%0.0%0.0% COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 14 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-8: Proposed Wastewater Service Charges (Not Rounded) Existing Existing Proposed Line Customer Class 1/1/2025 1/1/2026 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 Units 1 Single-Unit Residential, Monthly Charge per Unit $52.00 $52.00 $63.47 $76.10 $91.42 $107.89 $125.47 $/Unit 2 Multi-Unit Residential, Monthly Charge per Unit $52.00 $52.00 $63.47 $76.10 $91.42 $107.89 $125.47 $/Unit 3 Gang Cesspools, Monthly Charge per Unit $25.00 $25.00 $31.61 $37.93 $45.52 $53.71 $62.31 $/Unit 4 5 Non-Residential 6 Monthly Base Rate Charge per Unit $54.00 $54.00 $78.67 $94.40 $113.28 $133.68 $155.06 $/Unit 7 Monthly Usage Charge per 1,000 Gallons 8 0 - 8 kgal $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $/kgal 9 8 - 15 kgal $7.50 $7.50 $7.50 $9.00 $10.80 $12.74 $14.78 $/kgal 10 15 - 30 kgal $9.00 $9.00 $9.00 $10.80 $12.96 $15.29 $17.74 $/kgal 11 >30 kgal $9.50 $9.50 $9.50 $11.40 $13.68 $16.14 $18.73 $/kgal 12 13 Hotels 14 Monthly Base Rate Charge $54.00 $54.00 $95.72 $114.86 $137.84 $162.65 $188.67 $/Unit 15 Monthly Usage Charge per 1,000 Gallons 16 all kgal 17 0 - 8 kgal $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $/kgal 18 8 - 15 kgal $7.50 $7.50 $8.85 $10.62 $12.74 $15.03 $17.44 $/kgal 19 15 - 30 kgal $9.00 $9.00 $10.35 $12.42 $14.90 $17.58 $20.39 $/kgal 20 >30 kgal $9.50 $9.50 $10.85 $13.02 $15.62 $18.43 $21.38 $/kgal 21 22 Private Haulers 23 Septage $64.00 $64.00 $100.00 $140.00 $180.00 $217.07 $251.80 $/500 gal 24 Cesspool $64.00 $64.00 $100.00 $140.00 $180.00 $217.07 $251.80 $/500 gal 25 Portable Toilets $64.00 $64.00 $84.00 $104.00 $127.00 $150.27 $174.31 $/500 gal 26 WWTP $64.00 $64.00 $95.00 $125.00 $155.00 $172.93 $200.60 $/500 gal COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 15 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-9: Proposed and Projected Wastewater Service Charges (Rounded) Existing Existing Proposed Line Customer Class 1/1/2025 1/1/2026 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 Units 1 Single-Unit Residential, Monthly Charge per Unit $52.00 $52.00 $63.00 $76.00 $91.00 $108.00 $125.00 $/Unit 2 Multi-Unit Residential, Monthly Charge per Unit $52.00 $52.00 $63.00 $76.00 $91.00 $108.00 $125.00 $/Unit 3 Gang Cesspools, Monthly Charge per Unit $25.00 $25.00 $32.00 $38.00 $46.00 $54.00 $62.00 $/Unit 4 5 Non-Residential 6 Monthly Base Rate Charge per Unit $54.00 $54.00 $79.00 $94.00 $113.00 $134.00 $155.00 $/Unit 7 Monthly Usage Charge per 1,000 Gallons 8 0 - 8 kgal $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $/kgal 9 8 - 15 kgal $7.50 $7.50 $7.50 $9.00 $10.80 $12.75 $14.80 $/kgal 10 15 - 30 kgal $9.00 $9.00 $9.00 $10.80 $12.95 $15.30 $17.75 $/kgal 11 >30 kgal $9.50 $9.50 $9.50 $11.40 $13.70 $16.15 $18.75 $/kgal 12 13 Hotels 14 Monthly Base Rate Charge $54.00 $54.00 $96.00 $115.00 $138.00 $163.00 $189.00 $/Unit 15 Monthly Usage Charge per 1,000 Gallons 16 0 - 8 kgal 0 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $/kgal 17 8 - 15 kgal $7.50 $7.50 $8.85 $10.60 $12.75 $15.05 $17.45 $/kgal 18 15 - 30 kgal $9.00 $9.00 $10.35 $12.40 $14.90 $17.60 $20.40 $/kgal 19 >30 kgal $9.50 $9.50 $10.85 $13.00 $15.60 $18.45 $21.40 $/kgal 20 21 Private Haulers 22 Septage $64.00 $64.00 $100.00 $140.00 $180.00 $217.00 $252.00 $/500 gal 23 Cesspool $64.00 $64.00 $100.00 $140.00 $180.00 $217.00 $252.00 $/500 gal 24 Portable Toilets $64.00 $64.00 $84.00 $104.00 $127.00 $150.00 $174.00 $/500 gal 25 WWTP $64.00 $64.00 $95.00 $125.00 $155.00 $173.00 $201.00 $/500 gal Notes: (1) All charges except Non-Residential and Hotel Usage Charges are rounded to the nearest dollar. This rounding retains the policy decision made by the COH County Council during the adoption of wastewater rates in 2019. (2) The Non-Residential Usage Charge is rounded to the nearest $.05. This rounding retains the policy decision made by the COH County Council during the adoption of wastewater rates in 2019. COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 16 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-10: Proposed and Projected Wastewater Service Charges: Percent Changes Proposed Line Customer Class 1/1/2027 1/1/2028 1/1/2029 1/1/2030 1/1/2031 1 Single-Unit Residential 21.2%20.6%19.7%18.7%15.7% 2 Multi-Unit Residential 21.2%20.6%19.7%18.7%15.7% 3 Gang Cesspools, Monthly Charge per Unit 28.0%18.8%21.1%17.4%14.8% 4 5 Non-Residential 6 Monthly Base Rate Charge per Unit 46.3%19.0%20.2%18.6%15.7% 7 Monthly Usage Charge per 1,000 Gallons 8 0 - 8 kgal 9 8 - 15 kgal 0.0%20.0%20.0%18.1%16.1% 10 15 - 30 kgal 0.0%20.0%19.9%18.1%16.0% 11 >30 kgal 0.0%20.0%20.2%17.9%16.1% 12 13 Hotels 14 Monthly Base Rate Charge 77.8%19.8%20.0%18.1%16.0% 15 Monthly Usage Charge per 1,000 Gallons 16 0 - 8 kgal 17 8 - 15 kgal 18.0%19.8%20.3%18.0%15.9% 18 15 - 30 kgal 15.0%19.8%20.2%18.1%15.9% 19 >30 kgal 14.2%19.8%20.0%18.3%16.0% 20 21 Private Haulers 22 Septage 56.3%40.0%28.6%20.6%16.1% 23 Cesspool 56.3%40.0%28.6%20.6%16.1% 24 Portable Toilets 31.3%23.8%22.1%18.1%16.0% 25 WWTP 48.4%31.6%24.0%11.6%16.2% COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 17 of 18 8/10/2026 Appendix B: Cost-of-Service Analysis and Rate Design Appendix B: Cost-of-Service Analysis and Rate Design Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Table COS-11: Backcalculation of Revenues Under Proposed Wastewater Service Charges Projected Wastewater Service Charge Revenues Line Customer Class FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 1 Single-Unit Residential $3,239,800 $3,958,392 $4,809,456 $5,796,520 $6,882,744 2 Multi-Unit Residential $5,847,004 $7,143,528 $8,679,960 $10,463,200 $12,426,040 3 Gang Cesspools $82,656 $103,632 $125,416 $151,840 $178,840 4 5 Non-Residential 6 Monthly Base Rate Charge $1,054,680 $1,435,392 $1,731,352 $2,090,880 $2,480,472 7 Monthly Usage Charge 8 0 - 8 kgal $0 $0 $0 $0 $0 9 8 - 15 kgal $205,223 $221,096 $267,965 $322,798 $382,487 10 15 - 30 kgal $396,234 $426,874 $517,225 $622,958 $738,385 11 >30 kgal $4,709,454 $5,073,649 $6,152,635 $7,414,417 $8,778,201 12 13 Hotels 14 Monthly Base Rate Charge $17,136 $25,788 $30,912 $36,876 $43,260 15 Monthly Usage Charge 16 0 - 8 kgal $0 $0 $0 $0 $0 17 8 - 15 kgal $8,332 $9,980 $12,086 $14,571 $17,245 18 15 - 30 kgal $19,618 $23,126 $28,015 $33,796 $40,051 19 >30 kgal $1,145,583 $1,345,030 $1,628,612 $1,963,194 $2,328,269 20 21 Private Haulers 22 Septage $526,072 $792,427 $1,082,840 $1,371,721 $1,647,315 23 Cesspool $79,648 $119,907 $163,760 $207,335 $248,789 24 Portable Toilets $93,563 $121,312 $150,973 $183,955 $218,040 25 WWTP $153,870 $219,450 $284,850 $343,252 $392,746 26 27 Total $17,578,872 $21,019,582 $25,666,057 $31,017,313 $36,802,883 28 Revenue Requirement $17,553,000 $21,274,239 $25,784,374 $31,055,351 $36,778,997 29 Delta, >0 = overcollect $25,873 ($254,657)($118,317)($38,038)$23,886 30 31 Overcollect from COS Rates $129,332 $790 $1,050 $796 ($1,593) 32 Overcollect from Non-Residential Adjustment $57 ($3,129)($4,914)$5,557 $25,405 33 Overcollect From Proposed Private Haulers Adjustment ($80,344)($196,921)($74,868)($9,956)$0 34 Subtotal $49,045 ($199,261)($78,732)($3,603)$23,811 35 Overcollect from Rounding, Calculated by Difference ($23,172)($55,397)($39,585)($34,435)$75 36 Total Overcollect from All Adjustments (Same as Line 29)$25,873 ($254,657)($118,317)($38,038)$23,886 COH Wastewater Rate Model 08102026 Appendix B Copyright 2026 All rights reserved Page 18 of 18 8/10/2026 Wastewater Rate Study – County of Hawai’i, Wastewater Division C-1 County of HAWAII Wastewater Rate Study Report 08102026 A Appendix C: Rate Study Supporting Calculations Appendix C - Non-Residential Bill Frequency Data Appendix C: Rate Study Supporting Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Bill Frequency Data for Non-Residential Customers and Hotels FY 22/23 Non-Residential Customers Metered Water Consumption Data, Excluding Identified Hotels Line FY 22/23 Number of Meter Reads Excludes Hotels FY 22/23 Metered Consumption for Bills in Each Usage Level No.kgal/mo Hilo Honokaa Kona Pahala Papaikou Total Hilo Honokaa Kona Pahala Papaikou 1 0 167 33 20 0 10 230 3.65%0 0 0 0 0 2 1 250 44 12 1 17 324 5.15%250 44 12 1 17 3 2 254 35 9 2 9 309 4.91%508 70 18 4 18 4 3 191 37 6 1 16 251 3.99%573 111 18 3 48 5 4 205 24 8 0 8 245 3.89%820 96 32 0 32 6 5 184 19 16 1 9 229 3.64%920 95 80 5 45 7 6 137 17 14 1 5 174 2.76%822 102 84 6 30 8 7 168 13 16 0 7 204 3.24%1,176 91 112 0 49 9 8 118 9 17 0 12 156 2.48%944 72 136 0 96 10 9 97 12 7 0 3 119 1.89%873 108 63 0 27 11 10 118 10 12 0 8 148 2.35%1,180 100 120 0 80 12 11 109 10 13 0 7 139 2.21%1,199 110 143 0 77 13 12 78 7 8 0 5 98 1.56%936 84 96 0 60 14 13 95 8 14 0 0 117 1.86%1,235 104 182 0 0 15 14 93 10 20 1 2 126 2.00%1,302 140 280 14 28 16 15 71 11 17 0 4 103 1.64%1,065 165 255 0 60 17 16 58 5 8 0 2 73 1.16%928 80 128 0 32 18 17 65 7 14 0 2 88 1.40%1,105 119 238 0 34 19 18 63 7 7 0 0 77 1.22%1,134 126 126 0 0 20 19 60 8 1 0 2 71 1.13%1,140 152 19 0 38 21 20 65 10 10 0 0 85 1.35%1,300 200 200 0 0 22 21 41 8 3 0 0 52 0.83%861 168 63 0 0 23 22 60 3 7 0 1 71 1.13%1,320 66 154 0 22 24 23 35 8 9 1 0 53 0.84%805 184 207 23 0 25 24 36 2 4 0 1 43 0.68%864 48 96 0 24 26 25 31 7 10 0 0 48 0.76%775 175 250 0 0 27 26 41 6 6 0 0 53 0.84%1,066 156 156 0 0 28 27 36 4 17 0 1 58 0.92%972 108 459 0 27 29 28 42 2 7 1 0 52 0.83%1,176 56 196 28 0 30 29 20 4 6 0 1 31 0.49%580 116 174 0 29 31 30 27 2 4 0 0 33 0.52%810 60 120 0 0 32 31 27 5 8 0 0 40 0.64%837 155 248 0 0 33 32 30 1 6 0 1 38 0.60%960 32 192 0 32 34 33 23 2 6 0 1 32 0.51%759 66 198 0 33 35 34 21 5 4 0 0 30 0.48%714 170 136 0 0 36 35 12 0 6 0 0 18 0.29%420 0 210 0 0 37 36 22 0 1 1 1 25 0.40%792 0 36 36 36 38 37 19 1 3 0 0 23 0.37%703 37 111 0 0 39 38 27 1 7 0 0 35 0.56%1,026 38 266 0 0 40 39 15 2 2 0 0 19 0.30%585 78 78 0 0 41 40 27 3 2 0 1 33 0.52%1,080 120 80 0 40 42 41 21 2 3 1 0 27 0.43%861 82 123 41 0 COH Wastewater Rate Model 08102026 Appendix C Copyright 2026 All rights reserved 1 of 5 8/10/2026 Appendix C - Non-Residential Bill Frequency Data Appendix C: Rate Study Supporting Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Bill Frequency Data for Non-Residential Customers and Hotels 43 42 14 3 6 0 0 23 0.37%588 126 252 0 0 44 43 22 1 6 1 1 31 0.49%946 43 258 43 43 45 44 12 1 7 0 1 21 0.33%528 44 308 0 44 46 45 18 1 5 0 0 24 0.38%810 45 225 0 0 47 46 23 0 5 0 0 28 0.44%1,058 0 230 0 0 48 47 17 2 8 0 0 27 0.43%799 94 376 0 0 49 48 18 0 6 0 1 25 0.40%864 0 288 0 48 50 49 15 0 7 0 1 23 0.37%735 0 343 0 49 51 50 11 1 8 0 0 20 0.32%550 50 400 0 0 52 51 14 2 4 0 0 20 0.32%714 102 204 0 0 53 52 15 1 2 0 0 18 0.29%780 52 104 0 0 54 53 18 1 5 0 0 24 0.38%954 53 265 0 0 55 54 9 0 4 0 1 14 0.22%486 0 216 0 54 56 55 14 0 5 0 0 19 0.30%770 0 275 0 0 57 56 9 0 5 0 1 15 0.24%504 0 280 0 56 58 57 7 1 6 0 0 14 0.22%399 57 342 0 0 59 58 10 0 6 0 1 17 0.27%580 0 348 0 58 60 59 14 0 2 0 0 16 0.25%826 0 118 0 0 61 60 12 1 8 0 0 21 0.33%720 60 480 0 0 62 61 8 0 4 0 0 12 0.19%488 0 244 0 0 63 62 10 1 3 0 0 14 0.22%620 62 186 0 0 64 63 12 0 4 0 1 17 0.27%756 0 252 0 63 65 64 13 1 3 0 0 17 0.27%832 64 192 0 0 66 65 13 0 7 0 0 20 0.32%845 0 455 0 0 67 66 13 1 5 0 0 19 0.30%858 66 330 0 0 68 67 9 0 3 0 0 12 0.19%603 0 201 0 0 69 68 12 0 6 0 0 18 0.29%816 0 408 0 0 70 69 11 1 2 0 0 14 0.22%759 69 138 0 0 71 70 5 1 3 0 0 9 0.14%350 70 210 0 0 72 71 10 0 4 0 0 14 0.22%710 0 284 0 0 73 72 7 1 8 0 0 16 0.25%504 72 576 0 0 74 73 14 0 4 0 0 18 0.29%1,022 0 292 0 0 75 74 11 0 6 0 0 17 0.27%814 0 444 0 0 76 75 7 0 3 0 0 10 0.16%525 0 225 0 0 77 76 8 1 3 0 0 12 0.19%608 76 228 0 0 78 77 8 1 2 0 0 11 0.17%616 77 154 0 0 79 78 5 0 5 0 0 10 0.16%390 0 390 0 0 80 79 3 0 5 0 0 8 0.13%237 0 395 0 0 81 80 10 0 5 0 0 15 0.24%800 0 400 0 0 82 81 8 1 2 0 0 11 0.17%648 81 162 0 0 83 82 8 0 5 0 0 13 0.21%656 0 410 0 0 84 83 6 0 2 0 0 8 0.13%498 0 166 0 0 85 84 5 0 2 0 0 7 0.11%420 0 168 0 0 86 85 7 0 2 0 0 9 0.14%595 0 170 0 0 87 86 2 0 1 0 0 3 0.05%172 0 86 0 0 88 87 9 0 4 0 0 13 0.21%783 0 348 0 0 COH Wastewater Rate Model 08102026 Appendix C Copyright 2026 All rights reserved 2 of 5 8/10/2026 Appendix C - Non-Residential Bill Frequency Data Appendix C: Rate Study Supporting Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Bill Frequency Data for Non-Residential Customers and Hotels 89 88 11 1 3 0 0 15 0.24%968 88 264 0 0 90 89 6 1 3 0 0 10 0.16%534 89 267 0 0 91 90 9 0 2 0 0 11 0.17%810 0 180 0 0 92 91 5 0 4 0 0 9 0.14%455 0 364 0 0 93 92 6 1 2 0 0 9 0.14%552 92 184 0 0 94 93 3 0 3 0 1 7 0.11%279 0 279 0 93 95 94 6 0 2 0 0 8 0.13%564 0 188 0 0 96 95 5 3 5 0 0 13 0.21%475 285 475 0 0 97 96 5 1 5 0 0 11 0.17%480 96 480 0 0 98 97 6 1 4 0 0 11 0.17%582 97 388 0 0 99 98 3 1 0 0 0 4 0.06%294 98 0 0 0 100 99 3 1 2 0 0 6 0.10%297 99 198 0 0 101 100 7 0 2 0 0 9 0.14%700 0 200 0 0 102 101 6 0 3 0 0 9 0.14%606 0 303 0 0 103 102 6 0 2 0 0 8 0.13%612 0 204 0 0 104 103 4 0 2 0 0 6 0.10%412 0 206 0 0 105 104 5 0 3 0 0 8 0.13%520 0 312 0 0 106 105 9 0 1 0 0 10 0.16%945 0 105 0 0 107 106 5 0 6 0 0 11 0.17%530 0 636 0 0 108 107 7 0 1 0 0 8 0.13%749 0 107 0 0 109 108 8 1 2 0 0 11 0.17%864 108 216 0 0 110 109 5 0 4 0 0 9 0.14%545 0 436 0 0 111 110 8 1 3 0 0 12 0.19%880 110 330 0 0 112 111 5 0 6 0 0 11 0.17%555 0 666 0 0 113 112 2 0 0 0 0 2 0.03%224 0 0 0 0 114 113 9 0 2 0 0 11 0.17%1,017 0 226 0 0 115 114 8 0 1 0 0 9 0.14%912 0 114 0 0 116 115 5 0 0 0 0 5 0.08%575 0 0 0 0 117 116 2 0 2 0 1 5 0.08%232 0 232 0 116 118 117 4 0 3 0 0 7 0.11%468 0 351 0 0 119 118 6 0 2 0 0 8 0.13%708 0 236 0 0 120 119 7 0 0 0 0 7 0.11%833 0 0 0 0 121 120 5 0 1 0 0 6 0.10%600 0 120 0 0 122 121 8 0 2 0 0 10 0.16%968 0 242 0 0 123 122 6 0 4 0 0 10 0.16%732 0 488 0 0 124 123 4 0 5 0 0 9 0.14%492 0 615 0 0 125 124 3 0 4 0 0 7 0.11%372 0 496 0 0 126 125 4 0 4 0 0 8 0.13%500 0 500 0 0 127 126 6 0 1 0 0 7 0.11%756 0 126 0 0 128 127 1 0 1 0 0 2 0.03%127 0 127 0 0 129 128 2 0 1 0 0 3 0.05%256 0 128 0 0 130 129 0 0 3 0 0 3 0.05%0 0 387 0 0 131 130 6 0 1 0 0 7 0.11%780 0 130 0 0 132 131 2 0 2 0 0 4 0.06%262 0 262 0 0 133 132 3 0 4 0 0 7 0.11%396 0 528 0 0 134 133 2 0 1 0 0 3 0.05%266 0 133 0 0 COH Wastewater Rate Model 08102026 Appendix C Copyright 2026 All rights reserved 3 of 5 8/10/2026 Appendix C - Non-Residential Bill Frequency Data Appendix C: Rate Study Supporting Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Bill Frequency Data for Non-Residential Customers and Hotels 135 134 3 0 3 0 0 6 0.10%402 0 402 0 0 136 135 4 0 5 0 0 9 0.14%540 0 675 0 0 137 136 2 0 3 0 0 5 0.08%272 0 408 0 0 138 137 3 0 1 0 0 4 0.06%411 0 137 0 0 139 138 3 0 0 0 0 3 0.05%414 0 0 0 0 140 139 1 0 3 0 0 4 0.06%139 0 417 0 0 141 140 5 0 3 0 0 8 0.13%700 0 420 0 0 142 141 4 0 1 0 0 5 0.08%564 0 141 0 0 143 142 2 0 1 0 0 3 0.05%284 0 142 0 0 144 143 6 0 6 0 0 12 0.19%858 0 858 0 0 145 144 4 0 0 0 0 4 0.06%576 0 0 0 0 146 145 0 0 1 0 0 1 0.02%0 0 145 0 0 147 146 2 2 5 0 0 9 0.14%292 292 730 0 0 148 147 2 1 0 0 0 3 0.05%294 147 0 0 0 149 148 3 0 1 0 0 4 0.06%444 0 148 0 0 150 149 2 0 1 0 0 3 0.05%298 0 149 0 0 151 150 0 0 2 0 0 2 0.03%0 0 300 0 0 152 >150 465 19 429 0 6 919 14.59%227,316 5,587 263,056 0 1,652 153 NA 3,622 366 1,195 12 76 0.00% 154 Total 8,136 828 2,352 24 228 6,297 327,400 12,635 299,278 204 3,290 642,807 155 156 Math Checks 8,220 840 2,508 24 228 768,500 157 TRUE 158 Difference 84 12 156 0 0 159 # of Hotels 7 1 13 0 0 160 161 COH Wastewater Rate Model 08102026 Appendix C Copyright 2026 All rights reserved 4 of 5 8/10/2026 Appendix C - Non-Residential Bill Frequency Data Appendix C: Rate Study Supporting Calculations County of Hawai`i Wastewater Division 2026 Wastewater Rate Study Bill Frequency Data for Non-Residential Customers and Hotels 162 FY 22/23 Hotel Metered Water Consumption Data (1) 163 FY 22/23 164 Acct No. (2)7/2022 8/2022 9/2022 10/2022 11/2022 12/2022 1/2023 2/2023 3/2023 4/2023 5/2023 6/2023 kgal System 165 260.89950.004 294 314 399 501 447 553 608 11 11 11 9 12 3,170 Hilo 166 260.94800.000 112 94 103 130 90 105 125 141 154 125 104 135 1,418 Hilo 167 260.96600.003 3,883 4,181 4,832 5,341 4,037 4,473 4,535 4,999 3,650 2,990 3,595 3,805 50,321 Hilo 168 260.97400.000 692 708 819 908 644 696 700 740 828 815 734 833 9,117 Hilo 169 857.99824.001 NA NA 294 NA 332 NA 266 NA 258 NA 208 NA 1,358 Kona 170 260.67100.000 18 NA 23 NA 17 NA 12 NA 16 NA 20 NA 106 Hilo 171 260.83500.001 299 339 351 375 216 157 249 249 325 286 271 333 3,450 Hilo 172 380.04900.031 14 NA 65 NA 78 NA 79 NA 83 NA 84 NA 403 Hilo 173 640.90200.000 NA 40 NA 36 NA 40 NA 29 NA 33 NA 37 215 Honokaa 174 850.00880.030 4,297 NA 4,291 NA 5,553 NA 5,104 NA 2,268 NA 6,157 NA 27,670 Kona 175 850.00890.030 1,986 NA 2,051 NA 1,965 NA 2,045 NA 1,922 NA 2,059 NA 12,028 Kona 176 850.01840.032 36 NA 21 NA 35 NA 49 NA 91 NA 49 NA 281 Kona 177 851.41600.001 23 NA 24 NA 21 NA 22 NA 23 NA 19 NA 132 Kona 178 851.41775.004 81 NA 86 NA 72 NA 75 NA 67 NA 55 NA 436 Kona 179 854.62700.000 41 NA 53 NA 296 NA 96 NA 104 NA 104 NA 694 Kona 180 857.97930.001 NA NA NA NA 74 NA 247 NA 115 NA 351 NA 787 Kona 181 857.98883.000 1,558 NA 1,728 NA 881 NA 947 NA 942 NA 765 NA 6,821 Kona 182 857.99280.033 2 NA 2 NA 1 NA 2 NA 1 NA 2 NA 10 Kona 183 857.99320.030 88 NA 112 NA 98 NA 94 NA 62 NA 45 NA 499 Kona 184 857.99600.032 497 NA 439 NA 757 NA 525 NA 515 NA 493 NA 3,226 Kona 185 857.99970.000 NA 625 238 516 NA 860 258 NA 486 NA 237 331 3,551 Kona 186 187 Tier 1 Consumption, Hotels, FY 22/23, kgal Tier 3 Consumption, Hotels, FY 22/23, kgal 188 Hilo 576 Hilo 919 189 Honokaa 48 Honokaa 89 190 Kona 568 Kona 1,008 191 192 Tier 2 Consumption, Hotels, FY 22/23, kgal Tier 4 Consumption, Hotels, FY 22/23 193 Hilo 479 Hilo 66,011 194 Honokaa 42 Honokaa 36 195 Kona 497 Kona 55,420 196 197 Total 125,693 198 TRUE Note: (1) COH billing data does not explicitly identify hotels. The accounts in this table were identified by FG Solutions from COH accounting data that appear to be hotels, based on either the account name or address. COH staff must identify the accounts that will be charged the hotel rate. (2) Account numbers are not printed. COH Wastewater Rate Model 08102026 Appendix C Copyright 2026 All rights reserved 5 of 5 8/10/2026