As part of the design for the Lafayette Consolidated Government’s North St. Antoine Extension Project in north Lafayette, two new road crossings over two existing drainage laterals (Gaston Coulee and Coulee Bend Lateral No. 1) are required within the limits of the alignment this new 1.5 mile concrete curb and gutter roadway. In addition to the detailed topographic, right of way and utility surveys conducted along the roadway alignment, detailed topographic surveys (cross sections, normal water surface elevations, etc) were performed along the lengths of both of these laterals in the areas upstream and downstream of the proposed roadway crossings. As the channels meander significantly in the immediate vicinity of the proposed roadway crossings, each bend in the stream needed to be defined to aid in the design of the improvements as well as for providing stream cross section data for the LCG’s “no-rise” analysis for the newly proposed structures. As part of the design task, the contributory drainage areas for both laterals were determined by field observation and by the use of available LiDAR data and USGS topographic maps. This data was then used to estimate the resulting flows/runoff for the 100, 50 and 25 year return interval storms using the SCS TR-55 method which were in turn used to determine the type (concrete arch) and size (12’ R x 36’S) of the structures to be constructed at each crossing.
North St. Antoine Street Coulee
Lafayette Consolidated Government
Land Surveying Civil Engineering