Our team used HEC-RAS 5.0 2D to model flooding for the 100-year storm for several different bridge configurations (varying from 40 to 120-foot bridges) and compared the results to current conditions. Our main focus was to identify how each of these scenarios changed the storm water flows downstream. Each scenario had its pros and cons. For example, a 40-foot bridge pushed flow towards an existing channel, while the 120-foot bridge helped maintain a closer resemblance to the existing conditions. By utilizing GIS, we were able to quickly, and graphically, show where each bridge increased/decreased the water depth. This visual depiction provided the City with all the necessary data to make an informed decision.

On the survey side, our team established horizontal and vertical control, set and located aerial mapping control points, performed topographic survey, and determined centerline, right-of-way, and property line locations.  We also wrote legal descriptions for right-of-way, drainage, and temporary construction easements for acquisition from the Arizona State Land Department.

Following a large (200-year storm event) that occurred towards the end of construction, it was determined that the drainage improvements functioned as designed and no major damage was reported.