In addition to the roadway and utility design effort involved in widening 1.4 miles of Callaghan Road between Bandera Road and Ingram Road in San Antonio, Pape-Dawson significantly lowered the channel invert to minimize velocities while increasing hydraulic conveyance and reducing the need for concrete rip-rap. We designed a stilling basin to facilitate a 15’ vertical drop from existing to proposed channel invert and gas mains. We used HEC-HMS and TR-55 to develop new runoff calculations, and HY-8 and HEC-RAS to design large oversized multiple-box culverts to convey runoff for the Zarzamora Creek structure and remove the low water crossing. Due to the presence of several utilities and hazardous material contamination, complex storm drain designs were required to minimize conflicts and special designs to accommodate hydraulic and energy grade lines.
