FINAL Sewer Master Plan and Rate Study: 2020 Update Hall County Public Works and Utilities February 2020 Sewer Master Plan and Rate Study: 2020 Update Table of Contents EXECUTIVE SUMMARY 1. INTRODUCTION ..................................................................... 1-1 1.1 Background and Study Areas ........................................................................... 1-1 1.2 Plan Objectives ................................................................................................. 1-3 1.3 Report Outline .................................................................................................. 1-3 2. EXISTING AND FUTURE CONDITIONS ....................................... 2-1 2.1 Existing System and Facilities .......................................................................... 2-1 2.2 Sewer Basins .................................................................................................... 2-3 2.3 Demographics .................................................................................................. 2-5 2.4 Land Use........................................................................................................... 2-8 2.5 Hydrology ........................................................................................................ 2-13 2.6 Water Quality .................................................................................................. 2-13 2.7 Policy Considerations ..................................................................................... 2-14 2.7.1 Water Use ....................................................................................... 2-14 2.7.2 Water Reuse ................................................................................... 2-14 2.7.3 Interbasin Transfer ......................................................................... 2-14 2.7.4 Increased Biological Loading .......................................................... 2-15 2.7.5 Nutrient Standards for Lake Lanier ................................................ 2-15 2.7.6 Climate Resiliency ........................................................................... 2-15 2.8 Planning Considerations................................................................................. 2-16 2.8.1 Reliability & Flexibility ..................................................................... 2-16 2.8.2 Ease of Implementation/Constructability ....................................... 2-17 2.8.3 Easement Considerations ............................................................... 2-17 2.8.4 Biosolids Considerations ................................................................ 2-17 3. WASTEWATER FLOW PROJECTIONS ........................................ 3-1 3.1 Planning Assumptions and Methodology ......................................................... 3-1 3.1.1 Per Capita Wastewater Generation................................................... 3-1 3.1.2 Per Acre Wastewater Generation Rates............................................ 3-2 3.1.3 Inflow and Infiltration ........................................................................ 3-3 3.1.4 Peaking Factor .................................................................................. 3-3 3.1.5 Septic to Sewer Conversion .............................................................. 3-3 3.2 Wastewater Forecasts ...................................................................................... 3-3 3.2.1 North Hall Build-Out Wastewater Flows ............................................ 3-3 3.2.2 South Hall Build-Out Wastewater Flows............................................ 3-8 February 2020 Table of Contents i Sewer Master Plan and Rate Study: 2020 Update 4. NORTH HALL STUDY AREA WASTEWATER COLLECTION AND TREATMENT ALTERNATIVES AND CAPITAL IMPROVEMENT PLAN ........ 4-1 4.1 Review of the 2011 Recommended Alternative .............................................. 4-1 4.2 Description of the Preferred Development Scenario........................................ 4-2 4.2.1 Collection .......................................................................................... 4-4 4.2.2 Treatment ......................................................................................... 4-6 4.3 Capital Improvement Plan ................................................................................ 4-8 5. SOUTH HALL STUDY AREA WASTEWATER COLLECTION AND TREATMENT SYSTEM PLANNED IMPROVEMENTS .............................. 5-1 5.1 Description of Development Scenario .............................................................. 5-1 5.1.1 Collection .......................................................................................... 5-3 5.1.2 Treatment ......................................................................................... 5-5 5.2 Capital Improvement Plan ................................................................................ 5-8 6. NORTH AND SOUTH HALL COUNTY STUDY AREA WASTEWATER COLLECTION AND TREATMENT SYSTEM COST SUMMARY .................. 6-1 6.1 Unit Cost Development ..................................................................................... 6-1 6.2 North Hall Projected Costs ............................................................................... 6-2 6.3 South Hall Projected Costs ............................................................................... 6-6 6.4 North and South Hall Projected Costs Summary ............................................ 6-12 6.5 Capital Improvement Plan Summary and Maps ............................................. 6-14 6.5.1 Phase I Capital Improvement Projects Summary and Maps .......... 6-17 6.5.2 Phase II Capital Improvement Projects Summary and Maps ......... 6-19 6.5.3 Phase III Capital Improvement Projects Summary and Maps......... 6-22 6.5.4 Phase IV Capital Improvement Projects Summary and Maps ........ 6-25 7. Financial Management System Study ........................... 7-1 7.1 Identified Alternatives....................................................................................... 7-1 7.2 Revenue Requirements and Projections .......................................................... 7-1 7.2.1 Operation and Maintenance Expenses – Assumptions .................... 7-1 7.2.2 General Assumptions ........................................................................ 7-2 7.2.3 Existing Wastewater User Rates and Connection Fees .................... 7-2 7.2.4 Customer Base – Existing Service Area ............................................ 7-3 7.2.5 Customer Base – Expanded Service Area ........................................ 7-4 7.2.6 Revenue Requirements – O&M Debt Service and Capital ............... 7-8 7.2.7 Capital Improvement Plan - Base Case............................................. 7-9 7.2.8 Capital Improvement Plan– Master Plan with Expanded Service Area ........................................................................................................ 7-10 ii Table of Contents February 2020 Sewer Master Plan and Rate Study: 2020 Update 7.2.9 Debt Service Payments – Master Plan with Expanded Service Area .................................................................................................... ….7-16 7.2.10 Wastewater Revenue Projections ................................................... 7-18 7.3 Summary of Wastewater Revenue and Expenditures .................................... 7-20 7.4 Sensitivity Analysis ......................................................................................... 7-24 7.4.1 Sensitivity Analysis Summary.......................................................... 7-29 7.5 Summary ................................................................. 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List of Tables Table 2-1: Population and Employment Projections and Annual Average Growth Rates.................... 2-7 Table 2-2: ARC Population and Employment Projections – North Hall Drainage Basins .................... 2-8 Table 2-3: ARC Population and Employment Projections – South Hall Drainage Basins .................... 2-8 Table 2-4: Comparison of Current and Potential Future Land Use in North Hall Study Area ........... 2-11 Table 2-5: Comparison of Current and Future Land Use in South Hall Study Area .......................... 2-12 Table 2-6: North Hall 303(d) Listed Streams ................................................................................... 2-13 Table 2-7: South Hall 303(d) Listed Streams ................................................................................... 2-13 Table 3-1: Wastewater Generation Rates based on District Water Demands for Hall County ............ 3-2 Table 3-2: Per Acre Wastewater Generation Rates Categorized by Land Use Type ............................ 3-2 Table 3-3: Projected Build-Out Wastewater Flows – North Hall Service Areas ................................... 3-4 Table 3-4: Projected Build-Out Wastewater Flows by Type – North Hall Service Area ........................ 3-5 Table 3-5: Projected 2030 and 2040 Wastewater Flows – North Hall Study Area ............................. 3-6 Table 3-6: Build-Out Flows for Pipe Segments – Proposed North Hall Collection System .................. 3-6 Table 3-7: Projected Build-Out Wastewater Flows – South Hall Service Areas ................................... 3-8 Table 3-8: Projected Build-Out Wastewater Flows by Type – South Hall Service Area ........................ 3-8 Table 3-9: Projected 2030 and 2040 Wastewater Flows – South Hall Study Area ............................ 3-9 Table