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12 <br /> Scope of Work <br /> Continued <br /> identified in Workshop 1, using the data collection worksheet in the Protocols <br /> document (Figure 4-1). <br /> City staff will collect stream survey data from other reaches identified as needing <br /> to be assessed in Workshop 1, and Otak's staff will spend one day to spot check <br /> the additional reaches inventoried by City staff for consistency to data collected <br /> together. Stream channels will be observed on publicly owned lands and on <br /> those private properties where the property owner has not prohibited access. <br /> 3.3.3 Field Observations of Selected Basin Issues <br /> Otak staff, accompanied by City staff, will perform Level 3 field observations for <br /> up to 40 basin issues, assuming 4 issues can be assessed in a 4-hour block of <br /> time. The water flow and water quality leads will spend an average of two field <br /> days each investigating up to 15 issues each, based on the issues identified as in <br /> Workshop 1. No additional in-stream field investigation is included in this task. <br /> 3.4 Hydrologic Modeling <br /> Otak will use the Western Washington Hydrologic Model (WWHM4), to produce a <br /> continuous time series of runoff data from the basins within the City and UGA limits. <br /> Peak flow rates will be extracted for use in the conceptual design of CIP projects. <br /> Modifications to the input needed for modeling the proposed drainage systems will <br /> include changes in land use associated with the future development (ultimate build-out). <br /> 3.4.1 GIS Support to HSPF-Based Model <br /> Otak will assemble the required existing land use data (soil type, slope of the <br /> basins, and landcover) from the City's GIS database. This assumes that Otak will <br /> use GIS to analyze the change of land uses from existing (2011), ultimate built- <br /> out, on a subbasin by subbasin basis based on the procedures presented in the <br /> Protocols document. The GIS analysis will be used by Otak to update land use <br /> information for input to the HSPF model for future land use. Spatial analysis <br /> software in GIS will be used to combine and define the land types for each <br /> drainage subbasin. Slope data will be based on best available GIS LiDAR data <br /> from the City. Otak will define existing forest, grass and impervious areas from <br /> satellite imagery using ERDAS and the procedures presented in the protocols <br /> document. <br /> 3.4.2 Planning Level Hydrologic Model Development <br /> Level 1 hydrologic modeling will be performed (per Table 5-1 of the Protocols) for <br /> each basin to define the approximate flood frequency peak flows and monthly <br /> average flows at several locations in each basin for basin characterization. The <br /> City of Everett—Surface Water Comprehensive Plan Phase 2 7 <br /> February 13, 2012 132 otak <br />