Final Basis of Planning Report







Basis of Planning
Environmental Impact
Facilities Plan



Final Basis of Planning Report
Table of Contents

Executive Summary.


Goals and Objectives.

Planning Area Characteristics.

Planning Projections.

Water Quality and Water Resources Issues.

Existing Wastewater Facilities and Programs.

Stakeholder Values and Concerns.

1                      Chapter 1 ONE Introduction

1.1       Background.

1.2       Goals.

1.3       Objectives.

1.4       Planning Method.

1.5       Public Involvement Program.

2                      Chapter 2 TWO Planning Area Characteristics

2.1       Introduction.

2.2       Planning Area definition.

2.2.1    20-Year Planning Area.

2.2.2    50-Year Planning Area.

2.2.3    Priority Sewer Service Area.

2.3       Physical Environment

2.3.1    Geography and Topography.

2.3.2    Geology and Soils.

2.3.3    Climate

2.3.4    Air Quality.

2.3.5    Critical and Sensitive Areas

2.3.6    Threatened and Endangered Species.

2.4       Water Resources.

2.4.1    Groundwater

2.4.2    Surface Water

2.4.3    Wild and Scenic Rivers.

2.4.4    Flood Hazard.

2.4.5    Wetlands.

2.4.6    Potable Water Supply.

2.4.7    Health Issues.

2.5       Human Environment

2.5.1    Population

2.5.2    Land Use.

2.5.3    Employment and Economy.

2.5.4    Agricultural Resources.

2.5.5    Archaeological, Historical and Cultural Resources.

2.5.6    Governmental Structure.

3                      Chapter 3 THREE Planning Projections

3.1       Introduction.

3.2       Planning Horizons.

3.3       Population and Land Use Forecasts.

3.3.1    Current Base Condition.

3.3.2    Existing Development to Be Served By Sewer Extensions.

3.3.3    Future Population Growth and Development Through 2020.

3.3.4    Future Population and Growth Beyond 2020.

3.4       Wastewater Flow Projections.

3.4.1    Definition of Terms.

3.4.2    Current Base Flow.

3.4.3    Projected Average Annual Flow.

3.4.4    Peak Flow Projections.

3.5       Wastewater Loading Projections.

3.5.1    Constituents of Concern.

3.5.2    Projected Average Wastewater Characteristics.

3.5.3    Peaking Factors.

3.5.4    Summary of Projected Loadings.

3.6       Impact of Demand Management

3.7       Allocation of Flows and Loadings to Major Sewer Basins.

3.8       Summary of Findings.

4                      Chapter 4 FOUR Water Quality and Water Resource Issues

4.1       Introduction.

4.2       The Spokane Valley - Rathdrum Prairie Aquifer System.

4.2.1    Location and Nature of the Aquifer

4.2.2    Hydrogeological Characteristics of the Aquifer

4.2.3    Interaction Between the Aquifer and the Spokane and Little Spokane Rivers 

4.2.4    Water Resource Issues.

4.2.5    Water Quality Issues.

4.2.6    Aquifer Protection Programs.

4.2.7    Technical Information Development

4.2.8    Summary of Key Regulatory/Public Health Measures.

4.3       Surface Waters.

4.3.1    Basin Characteristics.

4.3.2    Hydrology and Water Resource Issues.

4.3.3    Stream Classification and Water Quality Criteria.

4.3.4    Current Wastewater Discharges.

4.3.5    Impaired Water Quality.

4.3.6    Current or Pending Total Maximum Daily Load Programs.

4.3.7    Anticipated Effluent Quality Requirements for a New Surface Water Discharge 

4.4       Effluent Reuse

4.4.1    Status of Regulations.

4.4.2    Classes of Reclaimed Water

4.4.3    Irrigation.

4.4.4    Impoundments.

4.4.5    Setback Requirements.

4.4.6    Industrial and Commercial Applications.

4.4.7    Wetlands.

4.4.8    Streamflow Augmentation.

4.4.9    Groundwater Recharge.

4.5       Biosolids Management

4.5.1    Regulatory Authority.

4.5.2    Existing Regulations.

5                      Chapter 5 FIVE Existing Wastewater Facilities and Programs

5.1       Introduction.

5.2       Regional Integration of Wastewater facilities.

5.3       Wastewater Collection Systems.

5.3.1    Spokane County System.

5.3.2    City of Spokane System.

5.4       Wastewater Treatment Facilities.

5.4.1    Spokane County Facilities.

5.4.2    Spokane Advanced Wastewater Treatment Facility.

5.5       Spokane County Wastewater Management Ordinances.

6                      Chapter 6 SIX Stakeholder Values and Concerns

6.1       Stakeholder Interview Purpose.

6.2       Stakeholders Interviewed.

6.3       Stakeholder Priorities, Issues, and Concerns.

6.3.1    County Wastewater Collection.

6.3.2    County-City Institutional Arrangement

6.3.3    Combined Sewer Overflow Control

6.3.4    Other Wastewater Management Issues.

6.3.5    Wastewater Management Issues and Concerns.

6.3.6    Alternatives for Managing Treated Wastewater Effluent

6.3.7    Biosolids Management

6.3.8    Recycling of Biosolids and Effluent

6.3.9    Aquifer Protection Program.

6.3.10  Wastewater Treatment Plant Site Enhancements.

6.3.11  Wastewater Treatment Plant Siting.

6.3.12  Wastewater Management Alternatives Evaluation.

6.3.13  Public Education Techniques.

6.3.14  Planning Involvement

7                      Appendix A Species of Concern Designated by Washington State

8                      Appendix B Washington Heritage Register for Spokane County

Appendix B – National Register of Historic Places; Washington Heritage Register for Spokane County 

9                      Appendix C City of Spokane Effluent Quality Requirements.



List of Tables


Table ES‑1.  Projected Wastewater Loadings.

Table ES‑2.  Potential Effluent Quality Requirements.

Table 2‑1.  1997 Spokane County Economic Census Results.

Table 3‑1.  Population Projections.

Table 3‑2.  Projected Commercial and Industrial Development

Table 3‑3.  Projected Average Flow.

Table 3‑4.  Analysis of Dry Weather Non-Storm Peaking Factors for Spokane Valley Interceptor

Table 3‑5.  Projected Peak Wastewater Flow.

Table 3‑6.  Interceptor Sampling, Summary of Quarterly Sampling 1996 to 1999.

Table 3‑7.  Wastewater Loading Summary for Nearby Communities.

Table 3‑8.  Interceptor Metals Concentration, Summary of Quarterly Sampling, 1996 to 1999.

Table 3‑9.  Recommended Wastewater Loading Factors.

Table 3‑10.  Septage Characteristics.

Table 3‑11.  Projected County Septage Loading.

Table 3‑12.  Wasteload Peaking Factors for Nearby Communities.

Table 3‑13.  Projected Wastewater Loadings.

Table 3‑14.  Projected Peak Wastewater Flow By Service Area.

Table 3‑15.  Projected Wastewater Loadings By Service Area.

Table 4‑1.  Gaining and Losing River Reaches.

Table 4‑2.  Summary of Water Quality Data for Spokane Aquifer

Table 4‑3.  Fecal Coliform Water Quality Standards.

Table 4‑4. Toxic Substances Regulated in Water Quality Standards.

Table 4‑5.  Current Wastewater Dischargers.

Table 4‑6.  Constituents Listed in Ecology’s Final 1998 303(d) List

Table 4‑7.  Median Values of Hardness in Spokane River

Table 4‑8.  Anticipated Effluent Quality Requirements for New  Surface Water Discharges  (Monthly Average Values Unless Noted Otherwise)

Table 4‑9.  Summary of Treatment and Effluent Quality Requirements for Reclaimed Water Classes 

Table 4‑10.  Water Quality Requirements for Irrigation Applications.

Table 4‑11.  Water Quality Requirements for Impoundments.

Table 4‑12.  Setback Requirements.

Table 4‑13.  Water Quality Requirements for Industrial and Commercial Applications.

Table 4‑14.  Water Quality Requirements for Wetlands.

Table 4‑15.  Treatment and Water Quality Requirements for Direct Aquifer Recharge.

Table 4‑16.  Concentration Limits for Biosolids Applied to Land.

Table 4‑17.  Loading Rate Limits for Biosolids Applied to Land.

Table 5‑1.  Spokane Valley Interceptor Capacity.

Table 5‑2.  North Spokane Pumping Station Capacities.

Table 5‑3.  Spokane County Wastewater Treatment Facilities.

Table 6‑1.  Rating Response for Other Wastewater Management Issues.

Table A‑1.  Species of Concern Designated by Washington State.

Table C‑1.  Effluent Quality Requirements for the City of Spokane Wastewater Treatment Plant


List of Figures


Figure ES‑1.  Population and Commercial/Industrial  Development Projections.

Figure ES‑2.  Wastewater Flow Projections.

Figure ES‑3.  Simplified Schematic of Regional Collection and Treatment Facilities for Municipal Wastewater

Figure 1‑1. Major Planning Components.

Figure 2‑1. Spokane County Planning Area Average Monthly Temperature and Precipitation.

Figure 2‑2.  Spokane County Historical Population Trends.

Figure 2‑3.  Spokane County Median Household and Per Capita Income.

Figure 3‑1.  Spokane County Wastewater Flow Monitoring.

Figure 3‑2.  Spokane Valley Interceptor Flow, Summer 1998.

Figure 3‑3.  Spokane Valley Interceptor Flow, Summer 1999.

Figure 3‑4.  North Valley Interceptor Wastewater Characteristics

Figure 3‑5.  Spokane Valley Interceptor Wastewater Characteristics.

Figure 3‑6.  North Valley Interceptor Wastewater Metals.

Figure 3‑7.  Spokane Valley Interceptor Wastewater Metals.

Figure 4‑1.  Historical 30-Day Average Streamflow at the Spokane Gage (Meter Station 12422500)

Figure 4‑2.  Extreme 30-Day Average Streamflow at Spokane Gage 1941-1999 (Meter Station 12422500)

Figure 5‑1.  Simplified Schematic of Regional Collection and Treatment Facilities for Municipal Wastewater

Figure 5‑2.  Example Output from Hydraulic Model

Figure 5‑3.  City of Spokane Interceptor System Schematic


List of Drawings


Drawing ES-1.  Planning Area

Drawing ES-2.  Surface and Ground Water Sources

Drawing 2-1. Planning Area

Drawing 2-2.  North Sewer Priority Areas

Drawing 2-3.  Valley Sewer Priority Areas

Drawing 2-4.  Surface and Ground Water Sources

Drawing 2-5.  Geologic Hazards and Constraints

Drawing 2-6.  Air Quality Areas

Drawing 2-7.  Critical Areas

Drawing 2-8.  Flood Hazard

Drawing 2-9.  Wetlands

Drawing 2-10.  Zoning Area

Drawing 4-1.  Major Regional Water Resources

Drawing 4-2.  Subsurface Views of the Spokane Aquifer

Drawing 4-3.  Gaining and Losing Reaches

Drawing 4-4.  Municipal, Industrial, and Landfill Discharge Locations

Drawing 5-1.  Regional Conveyance and Treatment Facilities

Drawing 5-2.  Existing Wastewater Conveyance Facilities

Drawing 5-3.  SAWTP Site Plan

Drawing 5-4.  SAWTP Liquid Stream Schematic



                                    This site was last updated on:  Thursday November 08, 2001