Sand Creek Floodplain LOMR
Matrix Design Group was retained by Forest City Stapleton to accurately map the existing floodplain of Sand Creek through the former Stapleton Airport via a Letter of Map Revision (LOMR). The LOMR for Sand Creek from Quebec Street through Havana Street covers a distance of 13,600 feet, or 2.5 miles, and includes four intricate split flow sections. This is a very complicated floodplain reach with numerous split flow conditions.
This particular reach of Sand Creek includes five drop structures, nine bridges, and multiple retaining walls. The reach has undergone significant changes over time with the removal of the runway tunnels, construction of new pedestrian bridges, and general earthwork grading. The study conducted by Matrix utilized the most up-to-date topographic mapping and hydraulic modeling software to reanalyze the floodplain. It should be noted that the previously defined floodplain is 30-plus years old and did not provide adequate information for bridge design and site development.
Rather than edit the effective (regulatory) model, Matrix created an entirely new model of Sand Creek in HEC-GeoRAS format using detailed topographic mapping. The primary objective was to develop a hydraulic model of current conditions using current mapping for use in future floodplain mapping. The results of Matrix’s new 3-dimensional model, which utilized 2-foot contour interval topography, were compared against the effective model with differences noted. The new model was then linked in GIS to the topographic model to show 100-yr water surface elevations and depth of flooding.
This LOMR served as the base model for future developments of the new I-70 Interchange, the new Central Park Boulevard Bridge, the new RTD FasTracks Commuter Rail Bridge, the new UPRR Railroad Bridge, and the general development of Stapleton.
- Hydraulic Modeling and Analysis
- Floodplain Map Revisions (CLOMR, LOMR)