Lochsa Engineering provided the civil and flood control design for the entire 76-acre CityCenter project for MGM Mirage Group. The project site occupies a large area along the Las Vegas Boulevard, in the heart of the Las Vegas Strip.  The project design tasks included hydrologic modeling of the site and Tropicana Wash-North Branch watershed; design of a storm drain system to drain the network of roof drains for the entire project and tie it into an existing storm drain mainline within Las Vegas Boulevard; hydraulic modeling of the Tropicana Wash-North Branch Breakout flows through the project site and the design of a flood control plan against the Wash flows; and obtained Federal Emergency Management Agency (FEMA) approval for a Conditional Letter of Map Revision (CLOMR) application for the construction of the Tropicana North Branch Detention Basin (TNBDB), a 56-acre.ft Clark County Regional Flood Control District (CCRFCD) facility, to remove FEMA Special Flood Hazards Area designation for an area of more than 2.0 square miles.