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in the effective FIS. The baseline analysis documented in the WRC letter report was utilized for the <br />duplicate effective condition in the current study due to the unavailability of the effective FEMA FIS <br />hydraulic model. A copy of the WRC letter report is provided in Appendix A. <br />1.4 Data Collection and Mapping <br />Surveying of the Arkansas River channel and overbanks within the study area was conducted in <br />order to develop 1 -foot contour interval topography, shown in Figure 1.2. The surveying was conducted <br />by King Surveying, Inc. (KSI) of Windsor, Colorado in October 2008, July 2009, and November 2010. The <br />surveying provided topographic details associated with the US Highway 50 Bridge, the abandoned <br />railroad embankment, and the gravel pit berms in support of the hydraulic evaluations. Hydrographic <br />surveying was performed by KSI to define the bottom of the gravel pits for reclamation purposes. <br />Survey data was provided in the Colorado State Plane Coordinate System (NAD 83) and references the <br />North American Vertical Datum of 1988 (NAVD88). A conversion factor of +1.84 feet was provided by <br />KSI between the National Geodetic Vertical Datum of 1929 (NGVD29) and NAVD88. <br />Survey of the Valco property boundary was conducted by Cardinal Land Surveying, Inc. of <br />Pueblo, Colorado in September of 2010. Additional data collected by ACE includes the following: <br />• 1977 aerial photography, provided by Valco, Inc.; <br />• 2005 NAIP aerial photography; <br />• USGS quadrangle mapping; and <br />• As -built plans of the south and north bound Highway 50 Bridges, provided in Appendix B. <br />COVALCOO1_Phase 11 Report_082211.docx <br />1.5 ANdERSON CONSUITINq ENC{iNEERS, INC. <br />