MARCH 2014 FINAL DRAFT Riverside Park Water Reclamation Facility NLT Engineering Report/ Wastewater Facilities Plan Amendment No. 3 PREPARED FOR City of Spokane PREPARED BY WBG030514153650SPK Final Draft Riverside Park Water Reclamation Facility NLT Engineering Report/ Wastewater Facilities Plan Amendment No. 3 Prepared for City of Spokane Prepared by March 2014 Contents Section Page Acronyms and Abbreviations .................................................................................................................. vii Executive Summary ............................................................................................................................. ES-1 ES.1 Discharge Standards ............................................................................................................. ES-2 ES.2 Flows and Waste Loads ......................................................................................................... ES-2 ES.3 Alternatives ........................................................................................................................... ES-3 ES.4 Recommended Improvements ............................................................................................. ES-7 ES.5 Financial .............................................................................................................................. ES-11 ES.6 Environmental Compliance ................................................................................................. ES-11 1 Introduction ............................................................................................................................. 1-1 1.1 Problem Identification ........................................................................................................... 1-1 1.2 FPA3 Format .......................................................................................................................... 1-2 2 Description of Discharge Standards ........................................................................................... 2-1 3 Background Information ........................................................................................................... 3-1 3.1 Existing Environment ............................................................................................................. 3-1 3.1.1 Surface Waters .......................................................................................................... 3-1 3.1.2 Groundwater ............................................................................................................. 3-2 3.1.3 Geology and Geography ......................................................................................... 3-11 3.1.4 Air ............................................................................................................................ 3-12 3.1.5 Climate .................................................................................................................... 3-12 3.1.6 Floodplains .............................................................................................................. 3-13 3.1.7 Shorelines ............................................................................................................... 3-13 3.1.8 Wetlands ................................................................................................................. 3-13 3.1.9 Endangered Species/Habitats and Priority Species ................................................ 3-14 3.1.10 Public Health ........................................................................................................... 3-15 3.1.11 Prime or Unique Farmland...................................................................................... 3-15 3.1.12 Archaeological and Historical Sites ......................................................................... 3-15 3.1.13 Federally Recognized Wild and Scenic Rivers ......................................................... 3-16 3.1.14 Recreation and Open Space Alternatives ............................................................... 3-16 3.2 Demographics and Land Use ............................................................................................... 3-16 3.3 Existing Conveyance and Treatment Facilities ..................................................................... 3-20 3.4 Current Flows and Waste Loads .......................................................................................... 3-22 3.4.1 Current Flows .......................................................................................................... 3-22 3.4.2 Current Waste Loads .............................................................................................. 3-27 4 Future Conditions ..................................................................................................................... 4-1 4.1 Population Forecasts ............................................................................................................. 4-1 4.2 Future Wastewater Flows ...................................................................................................... 4-2 4.2.1 City of Spokane ......................................................................................................... 4-2 4.2.2 Spokane County ........................................................................................................ 4-2 4.2.3 CSO ............................................................................................................................ 4-3 4.2.4 Water Conservation .................................................................................................. 4-3 4.2.5 Future Wastewater Flows ......................................................................................... 4-4 4.3 Future Waste Loads ............................................................................................................... 4-4 FPA3 FRONT MATTER_FINAL_DRAFT.DOCX/WBG030514153650SPK III COPYRIGHT 2014 BY CH2M HILL, INC. CONTENTS, CONTINUED 5 Alternatives .............................................................................................................................. 5-1 5.1 NLT Alternatives ..................................................................................................................... 5-1 5.1.1 Additional Treatment and Discharge to the Spokane River ...................................... 5-1 5.1.2 Additional Treatment to Existing RPWRF Facilities ................................................... 5-3 5.1.3 Agricultural Land Application .................................................................................... 5-5 5.1.4 Urban Irrigation ......................................................................................................... 5-6 5.1.5 Stream Flow Augmentation/Groundwater Recharge ............................................... 5-7 5.1.6 Groundwater Recharge ............................................................................................. 5-7 5.2 Evaluation of Alternatives ...................................................................................................... 5-8 5.2.1 Economic Analysis ..................................................................................................... 5-8 5.2.2 Nonmonetary Analysis ............................................................................................ 5-10 5.2.3 Screening Analysis ................................................................................................... 5-12 5.3 Evaluation of Two Final Options ........................................................................................... 5-13 5.3.1 Evaluation of Two Final Options at 100 mgd Peak Flow Capacity .......................... 5-13 5.3.2 Evaluation of Two Final Options: 100-mgd Conventional Filtration and 50-mgd Membrane Filtration ............................................................................................... 5-17 5.4 Other RPWRF Improvements ............................................................................................... 5-56 5.4.1 Activated Sludge ...................................................................................................... 5-57 5.4.2 CSO Clarifier No. 6 ................................................................................................... 5-58 5.4.3 Solids-Handling ........................................................................................................ 5-58 5.4.4 Odor Control ............................................................................................................ 5-61 5.4.5 Infrastructure and Energy Efficiency Improvements .............................................. 5-62 6 Final Recommended Alternative ................................................................................................ 6-1 6.1 NLT Improvements ................................................................................................................. 6-1 6.1.1 Site Layout and Sizing/Design Parameters ................................................................ 6-1 6.1.2 Flow Diagram ........................................................................................................... 6-15 6.2 Other Improvements ............................................................................................................ 6-21 6.2.1 Stormwater, Parking, and Landscaping Improvements .......................................... 6-21 6.2.2 Silo Digester No.