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Blue Plains Tunnel


Blue Plains Advanced WWTP, Overlook Avenue Southwest, Washington, DC, USA

Project Overview
Project Name: Blue Plains Tunnel
Date Completed: 2016
Location: Blue Plains Advanced WWTP, Overlook Avenue Southwest, Washington, DC, USA
Project Status: Complete
Project Type: Water/Environmental
Project Subtype: WastewaterTunnel

Project Tags: water environmental civil electrical geotechnical hydraulics wastewater conveyance

Project Team

Project Details
About this project
Most of Washington DC has a combined-sewer overflow system. This means the sewer pipes are designed to collect rainwater runoff and domestic wastewater in the same pipe. Most of the time the combined sewer system transports all the wastewater to DC Water’s Blue Plains Advanced Wastewater Treatment Plant where it is treated and then discharged. But during heavy rainfall the volume in the combined sewer system exceeds the system capacity. When this happens the excess wastewater is discharged with no treatment. This type of system is common in older urban areas.

In DC, heavy rains also often caused flooding when the combined-sewer overflow system exceeded its capacity.

Under a 25-year, $2.6-billion program, the city is improving the system, including constructing five storage tunnels and improvements at the treatment plant. The first tunnel was the Blue Plains Tunnel. It is 24,200 feet (4.6 miles) long. The tunnel diameter is 26 feet and is made of reinforced concrete. Now during heavy rainfall, excess rainfall goes into the tunnel where it is stored and then later treated at the treatment plant
Who benefits from this project, and how?
Before the project, during large rainfall events, combined rainwater runoff and wastewater was discharged into the river without being treated. Now the excess water is stored and then treated before it is discharged. This benefits the residents, visitors, and wildlife along the river.
Environmental considerations
The Blue Plains Tunnel project is the first project of DC Water’s Long Term Control Plan. The plan is to construct a system of tunnels and diversion sewers that captures the combined sewer overflows that discharge to Rock Creek, Anacostia River, and Potomac River. The captured overflow will then be treated at DC Water’s Blue Plains Advanced Wastewater Treatment Plant. Once the plan is complete, the untreated overflow will be reduced annually by 96 percent throughout the system and by 98 percent for the Anacostia River. This will result in healthier rivers.
What's unique about this project?
The tunnel boring machine is called "Lady Bird". It cost $30M and was used from summer 2013 to summer 2015. It moved about 13 million cubic feet of soil, which would fill reflecting pool in front of the Lincoln Memorial 14.5 times. The machine was so steady that you did not feel any movement when standing on the ground above it.

Funding & Costs
Project cost: $$$$$
Funding notes: The project cost was $330M and was done as a design-build contract

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