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2. Field Reconnaisance <br />2.1. Conduct a field inspection with COUNTY staff to examine the characteristics of the <br />creek, culvert, and surrounding riparian corridor with respect to hydraulic, erosion, and <br />scour processes. The purpose of this inspection is to understand site hydraulics and <br />channel conditions, with an emphasis on determining appropriate culvert span and <br />potential scour countermeasures for the proposed crossing. It will be beneficial to <br />meet with the COUNTY surveyors on site during the site reconnaissance to discuss <br />where additional survey may be needed to support the hydraulic and scour analysis. <br />Field measurements will include: <br />2.1.1. Characterizing sediment size <br />2.1.2. Estimating channel/floodplain roughness <br />2.1.3. Culvert measurements <br />2.1.4. Assessment of existing scour protection <br />2.1.5. Documenting lateral and longitudinal erosion. <br />2.1.6. Identification of high water marks <br />2.1.7. Other relevant information to aid in assessment and design of the proposed water <br />crossing. <br />2.2. Determine appropriate culvert opening size and potential scour countermeasures for <br />the proposed crossing. <br />3. Hydrology <br />3.1. Hydrology for Storey Creek will be determined by reviewing: <br />3.1.1. Prior studies <br />3.1.2. USGS regression analysis <br />3.1.3. Basin comparison with nearby watersheds and anecdotal information provided by <br />COUNTY staff from previous high-flow events. <br />3.2. Conduct analyses to determine the discharges for the 2-, 10-, 25-, 50-, 100-, 200-, and <br />500 -year flood events. <br />4. Geomorphic Reach Assessment <br />4.1. Conduct a rapid geomorphic analysis using newly obtained survey information, <br />geotechnical reports, aerial photos, and findings from the field reconnaissance. The <br />purpose of this assessment is to determine if there have been significant geomorphic <br />changes over time which will need to be accounted for in the design of the proposed <br />water crossing. <br />S. Hydraulics <br />5.1. Provide support to COUNTY staff. COUNTY will perform hydraulic modeling to <br />ascertain the hydraulic characteristics necessary to support the design of the new <br />culvert crossing and potential scour countermeasures for the protection of the <br />roadway prism. The hydraulic model will be developed by the COUNTY using <br />topographic data collected by the COUNTY surveyor. The hydraulic model results can <br />be used to support permitting to show the proposed water crossing meets WAC 220- <br />660-190. <br />6. Bank Stability Assessment and Design <br />