Northeast Boundary Tunnel Project Photo Gallery


View of CSO-019 Construction Site
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Check out our highlight reel! Below are photos from the Northeast Boundary Tunnel Construction Sites. It's a view behind the mesh-covered fences. At each of the construction sites, we are building facilities to connect to the existing sewer system and to support the tunnel. Photos will be updated periodically to highlight the work we are doing at each site.
 

Quick Links to Photos

Mount Olivet Road NE Construction Site First Street Pumping Station Construction Site
W Street NE Construction Site T Street NW Construction Site
Rhode Island Avenue NE Construction Site Florida Avenue NW Construction Site
4th Street NE Construction Site R Street NW Construction Site

 

Mount Olivet Road NE Construction Site

There are two construction staging areas on Mount Olivet Road NE: Department of Public Works (DPW) parking lot on Mount Olivet Road; and the intersection of Mount Olivet Road and Capitol Avenue NE. In order to relieve chronic sewer flooding, DC Water will construct a diversion facility that will include a diversion chamber, a 25-foot diameter drop shaft, and other structures to convey flow from the existing sewer to the tunnel.


Receiving a concrete pour for dropshaft lift #10. A lift is a workable height of concrete to safely place in the shaft's formwork. For our thickness of final liner, it is typically about a 10 ft height. Note the yellow concrete hose next to the larger ventilation bag line. 
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The view down the dropshaft showing the cut out opening for the ventilation control connection.
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Guide wall forms prior to the concrete pour for eventual cement-bentonite panels that serve as temporary support for excavations.
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W Street NE Construction Site

The W Street NE Construction Site is located on the Department of Public Works property south of W Street NE. In order to relieve chronic sewer flooding, DC Water will construct a ventilation control facility that will include a ventilation channel, a 45-foot diameter junction shaft, and other structures to regulate airflow throughout the tunnel system.


Welder giving Chris the TBM fresh metal plating and tooling on cutterhead.
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Placing steel plate protection over Chris the TBM to allow for safe work below. The crew is refitting tools on the cutterhead while placing formwork for a  concrete lift pour of the dropshaft's final liner.
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Coring and probing the dropshaft wall prior to Chris the TBM mining through it.
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Rhode Island Avenue NE Construction Site

The Rhode Island Avenue NE Construction Site is located on Rhode Island Avenue NE near the 8th Place intersection. In order to relieve chronic sewer flooding, DC Water will construct a diversion facility which will include a diversion chamber, a 25-foot diameter drop shaft, and other structures to convey flow from the existing sewer to the tunnel.


"Potholing" the top 5 ft of soil to clear utilities prior to installing a deep geotechnical instrument called an extensometer that measures any movement in the ground as Chris the TBM approaches and passes under it.
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Installing additional jet grout columns for ground improvement.
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Welders working on the large diameter steel pipe called a "flume". This flume gets inserted into a cut section of the existing combined sewer so the new diversion chamber can be constructed while still maintaining service for customers.
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4th Street NE Construction Site

At this site, construction will occur along 4th Street NE north of the Rhode Island Avenue NE intersection. In order to relieve chronic sewer flooding, DC Water will construct a diversion facility that will include a diversion chamber, a 20-foot diameter drop shaft, and other structures to convey flow from the existing sewer to the tunnel. The 4th Street Diversion Facility is designed to convey a peak flow rate of 457.2 million gallons per day to the Tunnel System.


In the foreground is the exposed existing combined sewer. Lagging is installed above the pipe to support the ground during excavation. 
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The dropshaft is being prepared for the start of adit excavation from the bottom of the shaft.
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Start of braced excavation for the approach channel between the diversion chamber and drop shaft. View from the dropshaft towards the diversion chamber excavation. 
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First Street Pumping Station Construction Site

The First Street Pumping Station Construction Site is located at the intersection of Thomas Street NW and First Street NW. The First Street Tunnel (FST) serves as a large storage tank for the Bloomingdale sewer system during large storm events. After the storm, the Pumping Station pumps the combined sewage out of the FST to the existing sewer system. Once the Northeast Boundary Tunnel (NEBT) is connected to the FST, the Pumping Station will be decommissioned and demolished. The NEBT will convey the combined sewage from the FST to the Blue Plains Wastewater Treatment Plant.


The contractor, SIH, drilled holes through the top and bottom of the existing sewer, then stuck a pipe (the sleeve) through those holes and sealed pipes top and bottom. That sleeve gave us a clear pathway to drill through and then underneath the existing sewer to inject jet grout.
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SIH workers performing a confined space entry using tripod assistance into the DC Water sewer pipe on First St. NW.  This entry allowed pulling the sleeves through the pipe for the upcoming jet grouting of the ground beneath it.
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Pouring flowable fill to provide additional protection of existing utilities during construction. Note the yellow straps on the left providing a support cradle under the utility.
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T Street NW Construction Site

The T Street NW Construction Site is located at the intersection of T Street NW and Rhode Island Avenue NW. In order to relieve chronic sewer flooding, DC Water will construct a diversion facility which will include additional storm water inlets, a 15-foot diameter drop shaft, and other structures to convey surface runoff to the tunnel. The T Street Diversion Facility is designed to convey a peak flow rate of 116.1 million gallons per day to the Tunnel System.


Noise barriers attached to perimeter fencing at the T Street construction site. Noise is monitored daily for adherence to District noise limit statutes.
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Drilling to install observation wells used for collecting and testing groundwater samples and monitoring groundwater levels.
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Pouring concrete into steel casing for a secant pile.
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Florida Avenue NW Construction Site

Construction at this site will occur along 3rd Street NW and Florida Avenue NW. In order to relieve chronic sewer flooding, DC Water will construct a diversion facility that will include a diversion chamber, a 20-foot diameter drop shaft, and other structures to convey flow from the existing sewer to the tunnel. The Florida Avenue Diversion Facility is designed to convey a peak flow rate of 322.8 million gallons per day to the Tunnel System.


Construction team in the dropshaft building a platform to work from when they drill to install freeze pipes. 
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Drilling into the dropshaft before installing a horizontal freeze pipe. The pipes will freeze the ground providing temporary support to excavate the adit. 
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Looking south toward Florida Avenue NW. To limit impacts to neighborhoods, the contractor must carefully plan the sequence of construction activities to fit within the fence line.
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R Street NW Construction Site

The R Street NW Construction Site is located within the triangular park bounded by 6th Street NW, R Street NW, and Rhode Island Avenue NW. In order to relieve chronic sewer flooding, DC Water will construct a diversion facility which will include a diversion chamber, a 38-foot diameter drop shaft, and other structures to convey flow from the existing sewer to the tunnel. The R Street Diversion Facility is designed to convey a peak flow rate of 264 million gallons per day to the Tunnel System.


Clamshell excavator cutting a rectangular slot in the soil that will be filled with a cement-bentonite mix. These wall panels will form a large rectangular box for temp support of excavation so a diversion chamber can be constructed.
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Removing cement bentonite silos at the R Street site. The silos were used to store the cement bentonite mixture used to build slurry walls. 
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Removing cement bentonite (CB) storage silos. The CB slurry walls stabilize the soil for excavation of the dropshaft which will extend about 70 feet below ground.
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Northeast Boundary Tunnel Project: dcwater.com/NEBT