Rehabilitating Taxiway D and Connector Taxiways to Runway 3-21.
This project consisted of providing engineering design and bid phase services for the rehabilitation of parallel Taxiway ‘D’, shoulders, erosion control pavements, and connector taxiways to Runway 3-21 as these pavements had reached the end of their useful service life. Rehabilitation included milling and overlaying AC pavement, localized full-depth reconstruction, crack sealing and trench patching. In addition to this core scope of work, Dibble designed a custom extension to an existing box culvert on both sides of the taxiway.
TW ‘D’ is intersected by Airport Wash, a FEMA regulated Special Flood Hazard Area. Airport Wash currently crosses Taxiway ‘D’ and Runway 21 via a 9 barrel 10’ x 6’ concrete box culvert. The extension of the box culvert is recommended to meet current FAA standards, placing the headwalls outside of the TOFA. The drainage was evaluated for the extension of the existing box culvert using the Corps of Engineer HEC‐RAS v.5.0.3 computer program. The structure was designed to convey the FEMA effective 100‐year peak flow: 4,021 cfs.
Of concern was erosion upstream of the culvert where concrete encasement of a water and a sewer line have been exposed. It appears that the channel bed had fallen over a foot since their installation. To protect these utilities and the downstream channel bed from an erosive condition, grouted riprap has been designed between the encased utilities and the culvert face.
The proposed design does not increase water surface elevations or velocities upstream of the construction area. Downstream of the culvert riprap has been designed for the culvert outlet velocity.
Client Tucson Airport Authority
Location Tucson, AZ
Scope $7.44 M
Extension of the existing box culvert located under Taxiway ‘D’ is needed due to the new fillet at Taxiway ‘D2’ and the Service Road relocation. The existing spillway will be removed and runoff will be connected into a catch basin on the upstream end of the box culvert extension.