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Yelm Phase II WW Planning Scope.012207SCOPE OF WORK City of Yelm Evaluation of Wastewater Collection, Treatment, and Disposal Alternatives for the Thurston Highlands Development Parametrix will provide to the City of Yelm (City) completion of the previous wastewater evaluation (draft Technical Report) for the Thurston Highlands Master Planned Community. This work will include refinement of disposal systems evaluation previously provided and evaluation of two treatment plant alternatives, and comparison of two system alternatives. Tasks to be completed in this evaluation will include: Conduct analysis for two treatment plant alternatives that can be used to allow effluent disposal by groundwater recharge, assuming expansion of the City of Yelm wastewater treatment plant (WWTP) only. Disposal to groundwater would be near the City of Yelm WWTP. Further analysis of the collection system using either gravity or STEP collection systems including update the O&M costs for Alternatives 1 and 2 based on historical data from Yelm. Further analysis of the effluent conveyance assuming groundwater recharge. Further refinement of the approach, soil capacity, methods, and costs to discharge treated effluent into the groundwater around the existing WWTP, further soils evaluation at Thurston Highlands would not be completed. Combine the appropriate collection, treatment, and disposal alternatives into two complete system alternatives. Conduct a comparison of these two system alternatives using evaluation criteria to include construction and operation and maintenance costs, feasibility, treatment reliability, construction impacts, and mitigation needs. Facilitate a workshop with City of Yelm and appropriate EIS team members to review the system alternative evaluation and evaluation criteria. Prepare a Draft Technical Report to present the results of the evaluation. This Draft Technical Report will become a portion of the comprehensive evaluation of the impacts to the City of Yelm wastewater system that will be incorporated into the Environmental Impact Statement (EIS). Task 1 – Project Management and QA/QC Task Objective(s) To communicate with the City and project stakeholders, provide quality control and peer review for scoped tasks, and prepare monthly summaries of project work completed and budget spent. Approach Parametrix will perform the following tasks as part of Project Management: Coordinate with the City of Yelm, including possible attendance at the EIS Team collaboration meeting, specific City meetings to expedite evaluation of alternatives. Prepare monthly status letters including internal earned value (budget review). Coordinate with internal project team members and complete a quality control/quality assurance review for the Draft. Technical Report. Deliverables Monthly status letters. Task 2 – Wastewater Treatment Plant Analysis Task Objective(s) Identify appropriate and reliable wastewater treatment technologies that will allow effluent disposal by groundwater recharge, assuming expansion of the City of Yelm wastewater treatment plant (WWTP) only. Approach Conduct analysis of treatment technologies that can be used to allow effluent disposal by groundwater recharge, at the City of Yelm WWTP. For treatment involving expansion of the existing Yelm WWTP (Alternative 3-1 and 3-2 defined in the draft Technical Report): The analysis will assume that the existing wastewater treatment process will be expanded, including a sequencing batch reactor treatment process followed by tertiary filtration to achieve a Class A effluent that can be disposed of by groundwater recharge. The approach must also provide nitrification and denitrification and consistently and reliably achieve total effluent nitrogen of less than 10 mg/L. The organic, solids, and hydraulic loading capacity of the existing Yelm WWTP will be confirmed. Using loading projections developed during the previous phase, the additional needed capacity for treatment, disinfection, and solids management will be determined. Effluent disposal will be to groundwater near the City of Yelm. It is assumed that up to 1.0 mgd of effluent can be disposed by surface water discharge to the Centralia Power Canal or Nisqually River. When combined with a gravity sewer system, a headworks will be needed to capture added solids and screenings at the existing wastewater treatment plant. STEP system collection systems will not require headworks improvements. One treatment “package” will be developed and paired with the gravity collection alternative and another (same technology smaller plant due to reduced flow and organic load) paired with the STEP collection alternative. The capital and operation and maintenance costs will be estimated for each package along with other non-monetary issues such as reliability, environmental and construction impacts. Assumptions The intent is to confirm the feasibility of appropriate system alternative (collection, technologies but not commit to a specific process at this stage. A subsequent engineering report will be required by Ecology and refinement and selection of the treatment technology will be conducted at that time. Task 3 – Collection System Analysis Task Objective(s) To finalize capital cost and operational cost comparisons between gravity and STEP collection systems, this information will support selection of the system alternatives. Approach The analysis will finalize cost comparisons and include discussion on other decision factors such as reliability, start-up, operation challenges, and construction impacts. Task 4 – Effluent Conveyance and Discharge Analysis Task Objective(s) Complete the analysis of the effluent conveyance, and infiltration systems compatible with the appropriate two treatment alternatives. Finalize the approach, methods, and costs to discharge treated effluent into the groundwater. Refine the design criteria for effluent disposal to groundwater recharge in the City of Yelm only. Approach Using projected discharge limits, wastewater flows, and water quality criteria developed in the previous work, size conveyance and groundwater recharge disposal systems compatible with two of the four sub-alternatives: Alternative 3-1 – A gravity collection sewer would serve Thurston Highlands and convey flow to the City of Yelm WWTP and discharge to groundwater near the City of Yelm. Alternative 3-2 – A STEP collection sewer would serve Thurston Highlands and convey flow to the City of Yelm WWTP and discharge to groundwater near the City of Yelm. For treatment at the City of Yelm WWTP, disposal will be by groundwater recharge near the City of Yelm and up to 1.0 mgd disposed by surface water discharge to the Centralia Power Canal or Nisqually River. Assumptions The capacity of soils to accept flows will be based on existing data without field testing / investigation. Task 5 – Alternatives Comparison Task Objective(s) Develop appropriate collection, treatment, and disposal alternatives into two complete system alternatives and evaluate them based on selection criteria. Conduct a workshop with the City of Yelm to discuss comparison findings. Approach Using the findings developed in previous tasks, combine the appropriate collection, treatment, and disposal alternatives into two of four complete system alternatives discussed in the preliminary Technical Report: Alternative 3-1 – A gravity collection system would serve Thurston Highlands and convey flow to an upgraded City of Yelm WWTP and discharge to groundwater near the City of Yelm. Alternative 3-2 – A STEP collection system would serve Thurston Highlands and convey flow to an upgraded City of Yelm WWTP and discharge to groundwater near the City of Yelm. Prepare estimates of capital and operation and maintenance costs for each complete system alternative. Coordinate with City of Yelm staff to develop evaluation criteria for comparison of the system alternatives. Preliminary suggested criteria include construction and operation and maintenance costs, feasibility, treatment reliability, improvement phasing and operation challenges, construction impacts, traffic impacts, environmental permitting requirements, and mitigation needs. Prepare an evaluation matrix that establishes importance factors to the selection criteria and use the matrix to score and compare the alternatives. Refine the alternatives evaluation, criteria, and importance factors based upon the City guidance provided in the workshop. Task 6 – Technical Report Preparation Task Objective(s) To document the analysis completed for comparison of alternatives for wastewater collection, treatment, and disposal; and preparation of an Executive Summary for the complete Technical Report. Approach Parametrix will develop a draft Technical Report documenting the analyses performed in previous tasks. The City and Thurston Highlands will have the opportunity to review the draft Technical Report and provide comments. Review comments will be incorporated into the final Technical Report and prior to inclusion of the information into the draft EIS. Assumptions The draft Technical Report will have three reviews: City review of draft Technical Report., Parametrix will modify the document based upon City comments. City and Developer review of modified draft Technical Report, Parametrix will modify the document based upon comments. City and Developer review of Final Technical Report, Parametrix will modify the document based upon comments. Deliverables Draft Technical Report, 10 Copies. Modified Draft Technical Report, 10 Copies. Final Technical Report, 20 Copies.