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2 Preliminary FIRM the information is shown in the North American Vertical Datum of 1988 (NA VD). The average datum change from NGVD to NA VD in the Vail area is +5.0 feet. 4. The flood hazard area shown on Exhibit F is Buffehr Creek, which was studied by detailed methods. Middle Creek and Mill Creek West were also restudied by detailed methods. Therefore, these locations show appropriate cross-sectional data. 5. Timing is a key factor in determining the 30-cubic-feet-per-second (cfs) increase. The value has been checked and found to be appropriate. 6. Some of the crossings have been designed to handle the base (l-percent-annual-chance) flood discharge, and some are not capable of containing all of the water. The bridge data is factored into each hydraulic model. · Panel 0468 D-- The Buffehr Creek hydraulic model, profile, and map all indicate that the base flood is contained in the channel at Circle Drive but floods over the road at Chamonix Lane. · Panel 0469 D--AlI five crossings along Red Sandstone Creek, including Interstate 70 (1-70), are shown and labeled as "I % annual chance flood discharge contained in culvert" and are properly illustrated on the profile. In addition, Spraddel Creek passes under a parking lot just before passing under 1-70. This is shown on the profile and in the model. · Panel 0493 D-- The referenced Pitkin Creek crossings are shown and labeled as "I % annual chance flood discharge contained in culvert" and are properly illustrated on the profile. Specific Issues 1. Panel 0468 D- The new culvert has been shown as overtopped by the base flood. However, 212 cfs passes through the culvert, leaving only 8 cfs of flow over the top. The effective FIRM is shown in NGVD, and the Preliminary FIRM is shown in NA VD. The average datum change from NGVD to NA VD in the Vail area is +5.0 feet. 2. Panel 0469 D- The value has been checked and found to be appropriate. 3. Panel 0488 D- The 84-inch corrugated-metal pipe culvert on Mill Creek East is shown in the model and on the profile. A "culvert" label will be added to the map panel. The referenced letter dated September 17, 2003, from J.F. Sato and Associates (Sato) discusses a proposed bridge and recommends preparation of as-built plans following construction of the bridge. On June 8, 2004, Mr. Barrie provided the as-built drawing. The delineation of Mill Creek West has been corrected to show the base flood contained in this channel. 4. Panel 0656 D- The flood depth at BFE 7822 is approximately 6 feet, according to the topography of the City of Vail. The topography is at a 2-foot interval, which generally means that it is accurate within a tolerance of 1 foot. All of the above-described situations are within the I-foot accuracy limits of the supplied topography map. When creating the water-surface elevation profile, stream-bottom elevations were taken directly from the revised hydraulic model and seem very reasonable.