intersection at SL 335 / IH 27

SL 335 / IH 27

Aguirre & Fields is the designer of record on over 250 bridges across Texas and Oklahoma. After 20 years in practice, we have established a quality reputation.
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DC Water and Sewer Authority’s long term CSO control plan includes a system of tunnels to control combined sewer overflows into the Anacostia River, Rock Creek, and the Potomac River and transport those captured flows to the Blue Plains Advanced Wastewater Treatment Plant.

The Anacostia River Tunnel is one component of this long-term control plan. The project was completed in late 2017 and has contributed to an increased capacity of the District’s sewer system, significantly mitigating the frequency, magnitude, and duration of sewer flooding. It is also helping to improve the water quality of the Anacostia River.

Project Features

  • 12,500-foot long 23-foot diameter, reinforced concrete segmentally lined tunnel
  • Six shafts with various configurations that include hydraulic internal structures, vortex drop facilities, and diversion chambers
  • Two shafts constructed at CSO-019 and connected by an interconnecting tunnel constructed by Sequential Excavation Methods
  • Diversion chambers with connecting diversion sewers and approach channels at two shaft locations
  • Adit tunnels to connect the shafts to the tunnel at three shaft locations
  • Ventilation control facilities to regulate air flow in the tunnel system.


  • Sustainability Intiative of the Year (November 2017) from the International Tunneling and Underground Space Association (ITA-AITES)