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Yelm Phase II WW Planning Scope.011207SCOPE 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) a refinementcompletion of the previous wastewater evaluation (draft Technical Report) for the Thurston Highlands Master Planned Community. This work will include refinement of wastewater collection, treatment, and disposal systems systems evaluation previously provided and complete evaluation of the treatment plant, comparison of system alternatives, and implementation strategies for the preferred alternative. needed for the addition of the Thurston Highlands development to the City wastewater system. The Tasks to be completed in this evaluation will include the following: Conduct analysis and prescreening of treatment alternatives that can be used to allow effluent disposal by groundwater recharge, either by expanding the City of Yelm wastewater treatment plant (WWTP) or by constructing a new WWTP at Thurston Highlands. Disposal to groundwater would be either near the City of Yelm or at the Thurston Highlands. Further analysis of the four “Alternative-3” collection system sub-alternatives, using either gravity or STEP collection systems. Prepare construction and operation and maintenance (O&M) costs. Update the O&M costs for Alternatives 1 and 2 based on historical data from Yelm. Further analysis of the effluent conveyance and outfall pipelines that would be compatible with the appropriate treatment alternatives and conveyance sub-alternative. Further refinement of the approach, soil capacity, methods, and costs to discharge treated effluent into the groundwater. Combine the appropriate collection, treatment, and disposal alternatives into complete system alternatives. Conduct a comparison of these 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. Collaboratively develop a recommendation for the one suitable alternative for implementation. For the recommended alternative for implementation, work with the developer City of Yelm to estimate the sequence of development. Ddetermine phases for construction of the wastewater system improvements to accommodate the development. Develop a schedule of the costs of improvements over time and a recommended approach to improvement phasing. 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, and conducting a singletwo workshops for purposes of selecting the preferred alternative for implementation, and developing a implementation approach for the preferred alternative including payment provisions by the Developer, and construction phasing.. 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, either by expanding the City of Yelm wastewater treatment plant (WWTP) or by constructing a new WWTP at Thurston Highlands. Approach Conduct analysis and prescreening of treatment technologies that can be used to allow effluent disposal by groundwater recharge, either by expanding the City of Yelm WWTP or by constructing a new WWTP at Thurston Highlands. 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 focus will be on matching the treatment technology to 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 a 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 [confirm] 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 new 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. . For treatment involving constructing a new WWTP in Thurston Highlands: Evaluate one feasible treatment technologies technology to achieve a Class A effluent that can be disposed of by groundwater recharge. The selected technology must also provide nitrification and denitrification and consistently and reliably achieve a total effluent nitrogen of less than 10 mg/L. One of the Tthree technologies (joint selection between Parametrix and City of Yelm) will be concisely used in the evaluationevaluated: (1) SBR with tertiary filtration, (2) membrane bioreactors, and (3) activated sludge with tertiary filtration. (Tom maybe just 1 and 2? Other wise difficult to compare alternatives….maybe just 1 only???) Using organic, solids, and hydraulic loading projections developed during the previous phase for Thurston Highlands, preliminary facilities for disinfection and solids management will be developed. Effluent disposal will be to groundwater near in Thurston Highlands. When combined with a gravity sewer system, a new headworks will be assumed to capture added solids and screenings at the proposed 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 paired (same technology smaller plant due to reduced flow and organic loads) with the STEP collection alternative. The capital and operation and maintenance costs will be estimated for each package. Assumptions For facilities located at Thurston Highlands, all effluent must be disposed of by groundwater recharge and none can be disposed by surface water discharge. 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 – Finish Collection System Analysis Task Objective(s) To finalize capital cost and operational cost comparisons between gravity and STEP collection systems, Tthis information will support selection of the system alternatives. Approach Complete the analysis of the four Alternative 3 collection system 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. Alternative 3-3 – A gravity collection sewer would serve Thurston Highlands and convey flow to a new WWTP located at Thurston Highlands and discharge to groundwater within the Thurston Highlands area. Alternative 3-4 – A STEP collection sewer would serve Thurston Highlands and convey flow to a new WWTP located in Thurston Highlands and discharge to groundwater within the Thurston Highlands area. The analysis of the above sub-alternatives will use findings developed for treatment and discharge conducted in other tasks. Estimates of construction and O&M costs will be developed. The O&M costs developed for Alternatives 1 and 2 will be updated using historical data provided by the City of Yelm. Task 4 – Effluent Conveyance and Discharge Analysis Task Objective(s) Complete the analysis of the effluent conveyance, outfalls, and infiltration systems compatible with the appropriate treatment alternatives and conveyance sub-alternative. 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 and at Thurston Highlands. Approach Using projected discharge limits, wastewater flows, and water quality criteria developed in the previous phasework, size conveyance and outfall alternatives and groundwater recharge disposal systems compatible with the four Alternative 3 collection system 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. Alternative 3-3 – A gravity collection sewer would serve Thurston Highlands and convey flow to a new WWTP located at Thurston Highlands and discharge to groundwater within the Thurston Highlands area. Alternative 3-4 – A STEP collection sewer would serve Thurston Highlands and convey flow to a new WWTP located in Thurston Highlands and discharge to groundwater within the Thurston Highlands area. For treatment at the City of Yelm WWTP, disposal will be by groundwater recharge near the City of Yelm and up to 1.0 [confirm] mgd disposed by surface water discharge to the Centralia Power Canal or Nisqually River. If necessary, Parametrix would also evaluate and model outfall improvements that would increase mixing of the effluent within the Nisqually River. Outfall improvements, in addition to increased pipeline diameter to convey greater flows, could include design of an effluent diffuser (multi-port discharge) located further from the river bank. The detailed design of an outfall diffuser and permitting process for installation of an outfall within the Nisqually River would not be in this scope of services and likely could not be completed prior to submittal of the EIS. (Tom we can always add this work in later…not sure that the City would want that discussed at this time). For treatment in a new WWTP at Thurston Highlands, it is assumed that all effluent must be disposed of by groundwater recharge and none can be disposed byzero discharge to surface water discharge. Estimate the hydraulic capacity of the subsurface at both the Yelm and Thurston Highlands disposal sites. Develop design criteria for groundwater recharge to minimize groundwater mounding, impacts on existing or proposed potable water wells and adjacent surface water sources., and interference with existing natural systems [?]. Two primary groundwater recharge options methods will be considered: infiltration galleries (trenches) in roadway right-of-way and rapid infiltration basins (similar to Cochran Park). Assumptions The capacity of soils to accept flows will be based on existing data without furtherwith limited field testing / investigation. Additional soil logs / pits will be provided by the Developer on the Thurston Highlands Site if requested. The City of Yelm and Ecology [Department of Water Resources] [Washington agency?]can provide locations for existing and proposed drinking water wells. (PGG already has these) Outfall improvements will not be modeled considered for the Power Canal / Nisqually River discharge. Task 5 – Alternatives Comparison Task Objective(s) Develop appropriate collection, treatment, and disposal alternatives into complete system alternatives and evaluate them based on selection criteria. Conduct a workshop with the City of Yelm and EIS team to develop a recommended system alternative. Approach Using the findings developed in previous tasks, combine the appropriate collection, treatment, and disposal alternatives into 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. Alternative 3-3 – A gravity collection system would serve Thurston Highlands and convey flow to a new WWTP located at Thurston Highlands and discharge to groundwater within the Thurston Highlands area. Alternative 3-4 – A STEP collection system would serve Thurston Highlands and convey flow to a new WWTP located in Thurston Highlands and discharge to groundwater within the Thurston Highlands area. Prepare estimates of capital and operation and maintenance costs for each complete system alternative. Coordinating Coordinate with City of Yelm staff, Ecology, and the EIS team, to develop evaluation criteria to for comparcomparison ofe 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. Facilitate a workshop with City of Yelm and appropriate EIS team members to review the system alternatives evaluation and evaluation criteria. RCollaboratively refine the alternatives evaluation, criteria, and importance factors based upon the City guidance provided in the workshop. Develop a recommendation for the one suitable alternative for implementation. Task 6 – Implementation of Recommended Alternative Task Objective(s) Using the recommended alternative developed in Task 5, assess how planned development will affect project phasing and recommend sequences for construction of wastewater system improvements. Develop cost schedules of anticipated costs. Approach The rate of growth of the City of Yelm and the Thurston Highland development, coupled with the selected alternative, will affect how the project will be phased and paid for. There are three logical components of phasing that need to be examined: collection, treatment, and disposal. For the Thurston Highlands, whether gravity or STEP collections systems are constructed will somewhat affect phasing, but in either case either the main pump station or main STEP pipeline will need to be constructed before homes can be constructed and occupied. As different areas are developed, the sub-basin collection or STEP system laterals will be constructed. If the Yelm WWTP is expanded, its existing capacity can be used prior to needing new capacity (allowing for the time needed for design, permitting, and construction). If a new WWTP at Thurston Highlands is to be provided, in the first few years of operation, it may receive very little flow, however a treatment facility and effluent conveyance and disposal systems must be constructed. This task will evaluate how the recommended alternative will be constructed over time. Participate in a meeting with the City of Yelm and the developer to learn the anticipated sequence of development. Using the estimated sequence of development, recommend phasing for construction of the wastewater system improvements to accommodate and keep pace with the development. Develop a schedule of the costs of improvements over time. Assumptions The developer can provide estimated sequences of development for different areas of the Thurston Highlands and be available to participate in a meeting. Parametrix staff will participate in one two half day meetings with the developer and the City of Yelm. Task 7 – Technical Report Preparation Task Objective(s) To document the analysis completed for development of alternatives for wastewater collection, treatment, and disposal; the evaluation and selection of the preferred alternative; and implementation include 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.