Northeast Boundary Tunnel Condition Surveys and Geotechnical Instrumentation

The design-build Northeast Boundary Tunnel (NEBT) project is the largest portion of DC Water’s Clean Rivers Project Long Term Control Plan to meet combined sewer overflow control objectives and flood relief in the District. The NEBT will connect to the Anacostia River Tunnel and will allow the captured combined sewage to be stored and conveyed by gravity to the Blue Plains Advanced Wastewater Treatment Plant for treatment prior to discharge to the Potomac River.

Condition surveys. EBA provided pre-construction condition surveys for sewers, storm drains, buildings, bridges, piers, and aerial track structures along the proposed tunnel alignment. These surveys helped quantify existing structure damage before construction and documented defects using photographs, video, and CCTV.

EBA surveyed 106 sewer and storm drains, vaults and valve structures for 55 water and 101 gas pipelines, 175 electric lines (aerial and underground), 32 communication structures, 37 buildings, and superstructure at two sections of elevated subway track.

EBA prepared work plans and safety plans, identified structures in the proposed construction activity zone, and oversaw maintenance of traffic. EBA also assisted with outreach to property and utility owners.

Geotechnical instrumentation. EBA provides work plans, instrumentation drawings, submittals, RFIs, and safety plans for geotechnical instrumentation. EBA has installed 108 utility monitoring points above various utilities, 47 inclinometers, 31 vibrating wire piezometers, structural and ground monitoring points, 36 observation wells, and 230 vibrating wire extensometers.

Our survey team provides daily survey monitoring of various instruments and provides 24/7 survey monitoring at critical locations.


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