Mill Creek Drainage Relief Tunnel

Ardurra provided construction management and observation services for Dallas's Mill Creek Drainage Relief Tunnel, a massive 30-foot diameter tunnel extending approximately 5 miles underground at depths of 70-150 feet. The project addressed critical urban drainage needs through advanced tunneling technology, creating an underground stormwater conveyance system from White Rock Creek outfall westward to the US 75 and Woodall Rodgers intersection.

The tunnel system was bored through Austin Chalk with the initial 9,200 feet excavated into a 35-foot horseshoe configuration and lined with 15 inches of non-reinforced concrete. Operating as an inverted siphon, the tunnel features an elevation difference of approximately 60 feet between the upstream end and the White Rock Creek outfall, creating natural hydraulic flow dynamics.

Key Construction Management Services:

• Managing 5-mile underground tunnel construction with 30-foot diameter boring through Austin Chalk at 70--150-foot depths

• Overseeing specialized excavation process, converting an initial 9,200 feet to a 35-foot horseshoe tunnel configuration

• Coordinating 15-inch concrete lining installation throughout the storm drainage tunnel, providing structural integrity and flow capacity

• Managing inverted siphon design with 60-foot elevation differential, creating natural hydraulic flow from upstream to outfall

• Supervising White Rock Creek outfall construction featuring a 46-foot diameter shaft approximately 110 feet deep

• Coordinating five drainage intake points strategically located throughout the tunnel alignment for comprehensive stormwater collection

• Providing comprehensive observation services, ensuring quality control and safety compliance throughout complex underground construction

The project demonstrated advanced urban drainage engineering while providing Dallas with critical flood control infrastructure. The underground approach minimizes surface disruption while creating substantial stormwater capacity, supporting downtown development and flood risk reduction.