DC Clean Rivers Project (DCCRP) involves the construction of a 12 miles long, 23ft diameter tunnel with 100+ ft deep shafts, secondary micro tunnels and pump stations to reduce the combined sewer overflow (CSO) by 98 percent. The entire project is divided into 26 tunnel segment sub projects called Divisions (A through Z).
Since 2008, AECOM has supported the project through:
• Borehole Geophysical Logging of 40+ borings including High Resolution Optical Televiewer®, High Resolution Acoustic Televiewer®, and 3-Arm Caliper
• Downhole and crosshole seismic surveys for design investigations at multiple tunnel shafts
• Seismic refraction, reflection and MASW surveys to support terrestrial tunnel alignment and design investigations
• Marine seismic reflection, bathymetric and magnetic surveys to support river tunnel alignment and design investigations
• MASW survey to delineate paleochannel along cut and cover tunnel alignment
• Bathymetric, side scan sonar, and marine magnetometer at combined sewer outfalls
• Utility avoidance and subsurface obstructions surveys including electromagnetic, magnetic and ground penetrating radar surveys at geotechnical boring locations for terrestrial and river borings
• Pre-constructions surveys at structures adjacent to planned tunnelling, open cut and shaft construction sites
• Pressure meter testing in terrestrial and river borings
• Unexploded ordnance (UXO) and munitions and explosives of concern (MEC) avoidance surveys (electromagnetic and magnetic surveys) at designated boring locations
• MASW and horizontal to vertical spectral ratio (HVSR) surveys to assess subsurface conditions at planned facilities in complex urban environments
AECOM utilized of a Robertson Geo Micrologger 2 data logger, Mini Winch, High Resolution Acoustic Televiewer® and 3-Arm Caliper logging probes to acquire borehole geophysical data in 40+ boreholes. The data, one portion of the project’s larger geophysical and geotechnical program helped to characterize site geologic conditions.
