• Bridge 5 is located within a FEMA Special Flood Hazard Area (SHFA) which is a Zone A approximate study area for Yaeger Finley Manard Ditch. FEMA has not determined base flood elevations (BFEs) or delineated a floodway for Yaeger Finley Manard Ditch at the subject location, however, the area is also an IDNR Approximate Floodway.
• According to U.S. Geological Survey (USGS) StreamStats, the drainage area to Bridge 5 is approximately 6.42 square miles at the crossing of CR 850 North. The drainage area will be verified as part of the Project's hydrologic assessment; however, the watershed is anticipated to be greater than one-square-mile, and as such the tributary would be classified as a Major Drainage System.
• GAI has included time for conducting a hydrologic assessment to estimate peak discharges to the Project site. Review of mapping and aerial imagery indicated that the StreamStats drainage area listed above is likely accurate, however, the StreamStats flows are higher than those utilized in DNR's HEC-RAS model for Yaeger Finley Manard Ditch. Thus, a hydrologic assessment using methodology appropriate for the watershed size will be utilized to estimate peak flow rates to the Project structure.
• The proposed structure location is within a rural area and has a drainage area of less than 50 square miles. While there are residential structures near the crossing preliminary review of hydraulic data indicates that these structures are likely outside the floodway and floodplain for Yaeger Finley Manard Ditch. Thus, it is assumed that the Project will meet the rural exception for a CIF in a floodway permit. As such, coordination with the IDNR is not anticipated to be required for confirmation of modeling approach or verification of peak flow rates, and the structure will be designed according to local (County) standards.
• There are two approximate HEC-RAS models for Yaeger Finley Manard Ditch from the IDNR Hydraulic Modeling Library, however neither include the existing bridge structure and the peak flow rates are inconsistent with the USGS StreamStats assessment. Thus, these models will be considered in the project hydraulic modeling efforts as applicable, but an updated, geo-referenced HEC-RAS model will need to be developed considering survey data, hydraulics through the existing bridge, and more recent topography to establish existing BFEs through the subject crossing.
• Due to the size of the existing structure and hydraulic conditions and the crossing, the existing conditions for the Ditch are proposed to be evaluated in a single HEC-RAS model, which will be created from a combination of publicly available contour data (LiDAR) and topographic survey in the Project area. The structure and roadway coding with the existing conditions model will be modified to create the proposed conditions model. GAI's scope also includes complete QA/QC of existing and proposed HEC-RAS models.
• The proposed replacement option will be evaluated using the IDNR General Guidelines for Hydrologic-Hydraulic Assessment of Floodplains and local guidelines as applicable. Options will be sized according to the 1% EP peak discharge and local permit requirements. If it is not feasible to pass a 1% EP or provide the requested two feet of freeboard, the replacement will be designed to pass a smaller design flow as comparable to but improved from existing conditions.
• The replacement structure is anticipated to be an aluminum box culvert, which will not require scour analysis. Riprap outlet protection and sumping will be designed according to typical design standards, and sumping will be coordinated with Delaware County.
• Results of the existing and proposed hydraulic analysis will be summarized in an abbreviated report and submitted to Delaware County for review and approval.

GAI will lead coordination, application, and tracking of all applicable environmental permits required for the Project. Preparation of regulatory permits will include demonstrating compliance with Section 7 of the Endangered Species Act (ESA). Additionally, a delineation and assessment of potential "Waters of the