DC Water at Work: Collaboration for Common Cause

DC Water owns hundreds of miles long masonry sewer, typically in congested areas packed with many linear assets of different owners. The integrity management of such old masonry pipe mandates a unique mindset in condition and adjacent construction impact assessment, prior, during, and after adjacent construction. In July 2021, DC Water discovered damage to a 39″ × 56″ brick sewer. A DC Water team launched into emergency response action in steps to prevent such localized damage of “bottom fall-out” from becoming a cause of street sinkhole. (1) By collaborating with peer agencies, we convinced the owner of the hand tunnel to fill it solid with flowable fill; (2) By in-depth knowhow of masonry sewer, we deployed extended chemical grouting to solidify the compromised bedding; and (3) By hydraulic modeling, we clarified which structural rehabilitation solution would not cause surge in the sewer. With above mitigation, DC Water successfully achieved our goal and prevented a sinkhole from forming relating to the brick trunk sewer that was damaged by an adjacent construction by others. This case study will share a few critical knowhows for integrity management of buried masonry asset in congested street.