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tit tit . South Platte River - Gloveville Phase III Model Study & Design Considerations David Love, Steven Abt, Nancy Love, and Thomas Brisbane 1999 CASFM Conference, September 22-24, 1999 ABSTRACT A project has been ongoing to remove approximately 300 acres of the Globeville neighborhood (near Franklin Street and the South Platte River in Denver, Colorado) from the 100-year floodplain of the South Platte River. The Phase III portion of the project will remove the Burlington Ditch and O'Brian diversion dam downstream of Franklin Street, construct a headgate approach channel, construct a new diversion dam upstream of Franklin Street, construct a trail underpass at Franklin Street, construct a new pedestrian bridge, remove and replace the Union Pacific Railroad bridge downstream of Franklin Street, and remove and reconstruct a the 30-inch Denver Water Department water line. The dam structure will incorporate a boat chute, serve as a grade control weir and assure minimum flows are diverted to the Burlington Ditch. Also included is scour protection for bridge piers, abutments, and appurtentant features. Because of the complexity of the river reach, a physical model was utilized in conjunction with numerical modeling approaches to better understand the hydraulics of the proposed river reach modifications and provide guidance for the final design. A 1 :20 Froude scale model (model to prototype) that incorporated the proposed river modifications was constructed in the Hydraulics Laboratory at Colorado State University. A series of 52 tests was performed to evaluate the numerous design structures/features over a range of hydrologic flow conditions including 2-year, 10-year, 50-year and 100-year flood events. In addition, tests were conducted to detennine the qualitative effects of sediment, ice, trash, and varying tailwater conditions on the perfonnance of the proposed structures/features integrated into the model. Tests were also perfonned to evaluate the scour potential at the Franklin Street Bridge. The presentation will present the study background and objectives, infonnation pertaining to the construction, modification and operation of the physical model, the model findings and recommendations, and how the findings were integrated into the final design. David Love & Nancy Love: Love & Associates, Inc, 841 Front Street, Louisville, CO 80227, 303-673-9795, LoveAssociates@tesser.com. Steven Abt & Thomas Brisbane: Engineering Research Center, Colorado State University, Fort Collins, CO 80523, 970-491-8657, sabt@engr.colostate.edu.