3.1        Introduction

A wide range of alternatives was considered for meeting Spokane County’s wastewater management requirements.  This chapter describes the evaluation process used and identifies the alternatives considered.  A detailed discussion and comparison of the most feasible alternatives is presented in Chapters 4 through 7.  A summary of the preferred wastewater management concept is presented in Chapter 9.

3.2        Evaluation Process

Alternatives were identified and evaluated through an interactive process involving County staff, consultant staff, representatives from resource and regulatory agencies, City of Spokane staff, the Spokane County Water Quality Advisory Committee (WQAC), the Spokane County Board of County Commissioners and the general public.  Major elements of the evaluation process are described below.  More detailed discussion of the public involvement process is presented in Chapter 8, and further discussion of the Environmental Impact Statement (EIS) process is presented in the separately bound EIS report.   Error! Reference source not found., Error! Reference source not found., lists attendees and identifies discussion topics at key review meetings during the course of the study.

Define Process Methodology.  To provide a consistent planning basis and to gain timely input from stakeholders, HDR and County staff developed an evaluation methodology for the wastewater management concepts.  This resulted in an integrated decision-making/public involvement process.

Initial Inter-Agency Symposium.  In August 2000, a workshop was held with regulatory and resource agencies concerned with regional water quality and wastewater management issues.  This meeting also included a number of municipal and industrial dischargers to the Spokane River.  The workshop focused on the Basis of Planning findings and identified the range of alternatives likely to be evaluated.  Participants were invited to suggest additional alternatives for consideration.

Initial WQAC Meeting.  In August 2000, an introductory meeting was held with WQAC members to summarize the Basis of Planning study and to solicit input on the types of alternatives that should be considered.

Initial Public Meeting, EIS Scoping Session.  In September 2000, a public meeting was held to present key findings of the Basis of Planning effort.  This meeting also identified the types of wastewater management concepts that were likely to be evaluated.  A question/answer session and a written questionnaire solicited the public’s input on their initial reaction to the concepts and their recommendations for additional alternatives to consider.  This initial public meeting also served as the formal Scoping Session for the EIS.

Evaluation Criteria.  Based on input from County staff, Ecology staff, consultant staff, stakeholder interviews and the public meetings held to date, a set of criteria was developed for use in evaluating alternatives.  These are listed in Table 3‑1.  Except for cost, these criteria were applied on a non-weighted, qualitative basis.

Table 3‑1.  Evaluation Criteria

1.                    For treatment location alternatives, the risk criterion was replaced by a “financial risk” criterion.  This is explained in Chapter 6.

2.                    For treatment location alternatives, the environmental impact and community impact criteria were combined into a single “impact” criterion.

Brainstorm and Screen Ideas.  In October 2000, a three-day workshop was conducted to identify potential alternatives for managing wastewater generated in the Spokane County Service Area. Following the brainstorm session, an initial screening step was conducted to eliminate ideas that were fatally flawed, technically unproven, excessively expensive or otherwise unworthy of detailed evaluation.

Detailed Development and Evaluation.  Alternatives surviving the initial screening step were evaluated in detail.  Facility sizing and cost estimating were based on a 25-year planning horizon, although consideration was given to expanding the concepts to meet 50-year growth projections.  Alternatives were compared based on cost and non-economic criteria.  Results were summarized in draft report chapters.

Second Round of Public, Inter-Agency and WQAC Meetings.  In January 2001, during development of the alternatives, a second round of workshops was held with regulatory and resource agencies, Spokane River dischargers, WQAC members and the general public.  These meetings identified the alternatives being evaluated in detail and presented initial observations on the advantages and disadvantages of the concepts, but did not present information on cost or results of the comprehensive evaluation.  The intent was to inform stakeholders as to the final alternatives being considered and to gain input as to whether the study was properly focused.

Review Workshops.  During the alternatives development process, meetings were conducted with County staff to review interim findings and refine the alternatives being evaluated.  As part of this process, participants compared the alternatives against the evaluation criteria.

Preliminary Preferred Wastewater Management Concept.  Following review of the various alternatives, the project team developed preliminary recommendations for the preferred wastewater management concept.  These recommendations are summarized in Chapter 9.

Review Workshops with City of Spokane, Ecology and WQAC.  In April 2001, individual meetings were held with City of Spokane wastewater management staff, representatives from the Department of Ecology and the WQAC to review the evaluation process, discuss the preliminary recommendations for the preferred wastewater management concept and solicit comments on how to improve the preliminary recommendations.

Briefing Workshop with Spokane County Board of County Commissioners (BOCC).  In early May 2001, the Spokane County BOCC was briefed on the status of the facilities planning effort, and provided an overview of the preliminary recommendations for the preferred wastewater management concept.

Third Round of Public and Inter-Agency Meetings.  In late May 2001, a third round of public and agency meetings was held to present the results of the evaluation and to identify preliminary recommendations.  A meeting was also held with the SCWQAC at this time.  Each group was asked to comment on the findings.

Decision Workshop. Following the meetings with the City of Spokane, Ecology, WQAC, BOCC, the public and agencies, the project team met to consider the comments received and to adjust the recommended plan in response to accepted comments.  Since each of the groups was generally supportive of the recommendations presented, only minor revisions were needed to produce a final plan.

Refinement of Preferred Wastewater Management Concept.  A plan was developed to guide implementation of the recommended wastewater management concept.  This effort included evaluation of financing methods, facility siting requirements, permitting and environmental documentation requirements, and public and private approaches for construction and operation.

3.3        Alternatives Brainstorming and Screening

During the brainstorming session, more than 80 ideas for wastewater management were identified.  During a subsequent screening session, the each idea received one of the following designations:

·        Retain.  Carry idea forward into detailed analysis.

·        Retain, merge with similar idea.  Valid idea, combine with one of the retained ideas carried forward into detailed analysis.

·        Retain, evaluate later.  Valid idea, evaluate during development of the implementation phase of the facility plan once a preferred wastewater management concept has been identified.

·        Retain, not in scope.  Valid idea, but outside of the scope for this study.  Address in concurrent or future studies.

·        Fail.  Idea is fatally flawed.  Do not carry forward to detailed analysis.

A full listing of the ideas identified is presented in Error! Reference source not found., Error! Reference source not found..  Table 3‑2 summarizes the number of ideas generated and the initial screening results.

Table 3‑2.  Summary of Initial Brainstorm and Screening Session

3.4        Detailed Evaluation of Alternatives

Development of a preferred wastewater management concept requires determination of the four components shown in Figure 3‑1.  Following the initial brainstorming and screening steps, the alternatives remaining in these management areas were developed in detail, and compared against evaluation criteria.  This section identifies the alternatives evaluated, presents major design criteria used in development of the alternatives, and describes the cost estimating methodology.

3.4.1        Summary of Alternatives Developed

Table 3‑3.  lists the alternatives considered for the four major components comprising the overall wastewater management program.

3.4.2        Design Criteria

An array of design criteria was established to guide development of the wastewater management alternatives.

Planning Horizon

Generally, the alternatives were developed and compared based on flow and loading projections for the year 2025.  This would allow nearly 20 years of operation following implementation.  Consideration was also given to the ability of the alternatives to handle projected flows and loadings in the year 2050.  This long-term view allows the alternatives to be compared with respect to expandability, and flexibility to meet future changes in land use, regulation and public perception.

Flows and Loadings

Flow and loading projections are summarized in Chapter 2, and are discussed in detail in the Basis of Planning Report.

Effluent Quality Requirements

The effluent quality requirements will vary for the range of effluent end use alternatives being considered.  Specific requirements are presented in Chapter 5 for each alternative.

Table 3‑3.  Alternatives Subjected to Detailed Analysis

 1.            Added during planning process in response to public comment.

Process Sizing Criteria

These criteria specify design loading rates and operating parameters for critical unit treatment processes.  Examples include clarifier overflow rates, aeration basin mixed liquor concentrations, and filter loading rates.  Where applicable, the Washington State Department of Ecology’s Criteria for Sewage Works Design ^[i] were used.  Otherwise, conventional design methodologies were used.

For sewers, year 2050 flow projections were used as the basis for design.  Sizing was based on a maximum water depth of 0.7 times the pipe diameter under peak flow conditions.

Reliability/Redundancy Criteria

For wastewater treatment and pumping stations, the redundancy criteria presented in Table 3‑4 were applied.

Table 3‑4.  Redundancy Criteria for Unit Treatment Processes

For wastewater force mains, redundant pipelines will not be provided; however, multiple pipelines may be needed to accommodate the range of flows expected over the life of the facility.

Standby power will be provided for treatment plants and pumping stations.  Treatment plant facilities will meet EPA’s Class I reliability requirements, with the added demand of keeping the biological process viable during a prolonged power outage.

3.4.3        Development of Costs

Capital Costs

Capital costs are expressed in January 2001 dollars (ENR Cost Index 6281), and should be viewed as “planning level” estimates.  These estimates are approximations made without detailed engineering or site-specific data.  Estimates of this type can be expected to vary from 50 percent less than to 30 percent more than actual final project costs. 

The sources of construction cost data are:

·        HDR’s ENVision cost-estimating program based on national cost curves that HDR developed for the U.S. EPA, adjusted to regional market conditions and 2001 dollars.

·        Recent construction costs for other, similar facilities, adjusted to regional market conditions and 2001 dollars.

·        Recent construction costs for the County’s pipeline and pump station projects, adjusted to 2001 dollars.

·        Equipment pricing from manufacturers, including installation, structure, and housing costs.

All capital costs include allowances for site work and yard piping; contractor mark-up; contingencies; and engineering, legal and administration costs.  The cost estimating procedure is presented in Table 3‑5.

Table 3‑5.  Illustration of Capital Cost Estimating Procedure

Operating Costs

Operating costs were developed for projected flow and loading conditions in 2015, the mid-point of the initial 20-year operating period.  The following unit factors were used:

·        Labor - $31.50/hour

·        Maintenance – 5% of installed equipment

·        Electrical power - $0.06/kwh

·        Natural gas - $0.83/therm

·        Aluminum sulfate – $120/ton

·        Polymer - $10/dry ton of dewatered sludge

Land Costs

Property acquisition costs were based on the following estimated land costs:

·        North County -$20,000/acre

·        Spokane Valley (highly developed areas) - $100,000/acre

·        City of Spokane (highly developed areas) - $140,000/acre

Present Worth Analyses