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Exhibit A <br /> FYZ <br /> a. Prepare a stormwater treatment site conditions memorandum to document findings of <br /> the data review and site reconnaissance inclusive of data gaps and supplemental data <br /> needs for the project design. <br /> 3. Provide hydrologic modeling using Western Washington Hydrology Model (WWHM) for <br /> conveyance and water quality treatment facility design: <br /> a. Confirm the delineation of tributary stormwater subbasins and combined storm sewer <br /> (CSS) subbasin stormwater to be separated for conveyance to runoff to treatment <br /> facilities (Subbasins LW-9, LW-10, LW-11, and CSS). <br /> b. Summarize subbasin land cover conditions (imperious and pervious forest/grass/wetland <br /> areas) and pervious area soils designations (outwash, till, saturated) in a drainage <br /> subbasins characterization table. <br /> c. Provide a detailed breakdown of the proposed drainage network with design flows <br /> computation at various nodes throughout the improved drainage system. <br /> d. Estimate storm drain conveyance design flows along with off-line/on-line water quality <br /> flows at the treatment site. <br /> 4. Advance the water quality design recommendations provided in the Lexington Avenue and <br /> Wetmore Avenue Storm Drainage and Water Treatment Improvements Feasibility <br /> Evaluation report: <br /> a. Evaluate if treatment flow storage attenuation will be beneficial and cost effective to <br /> optimize treatment facilities sizing and operations. If desired by the City, recommend <br /> how that storage could be integrated and configured within the treatment facilities layout. <br /> b. Provide pretreatment (hydrodynamic separator) and enhanced treatment facilities design <br /> for the selected proprietary treatment best management practice (Filterra Bioscape). <br /> 5. Prepare a draft technical memorandum that is up to ten (10) pages in length, including up to <br /> four (4) figures/exhibits to document: <br /> a. Preliminary design flows with runoff and treatment volumes as input to the hydrologic <br /> and design of the project conveyance, treatment, and high-flow bypass improvements <br /> b. Water quality treatment design <br /> 6. Prepare preliminary (30%) design drawings for the recommended stormwater treatment <br /> facilities design. <br /> 7. Prepare preliminary design specifications sections list for the stormwater treatment facilities. <br /> 8. Prepare an Engineer OPCC (AACE Class 3) <br /> 9. Prepare for and attend the following meetings: <br /> a. Up to two (2) stakeholder meetings with City staff that will be conducted via MS Teams <br /> (or other web-based virtual platform); up to four (4) consultant staff may attend each <br /> meeting: <br /> i. A one (1)-hour coordination and information review of the tributary subbasins, <br /> hydrologic analysis, and summarization of the water quality treatment concepts prior <br /> to preliminary design. <br /> ii. Workshop with City staff for up to two (2) hours in duration to present the findings <br /> from Subtask 410 Stormwater Conveyance Facilities Concept Design and Task 500 <br /> Stormwater Treatment Preliminary Design. <br /> Lexington Avenue Storm Drainage Improvements Preliminary Design Scope of Services <br /> 15 <br />