Emergency Engineering Services for the Monument Street Sinkhole,
Baltimore, MD



  • Inspection
  • Emergency Adjacent Building Support Design
  • Support of Excavation Design
  • Masonry Drainage Tunnel Repair Design
  • On-Site Engineering Support During Construction


Sabra Wang & Associates, Inc. (SAI) responded to an emergency call about a sinkhole due to a possibly failed 10 - foot diameter brick masonry storm drain. SAI personnel performed the confined space inspection of approximately 700 feet of the storm drain on July 25, 2012 at a depth of 40 feet below grade. SAI inspectors found that the storm drain had failed and partially collapsed, leading to the sinkhole. SAI was responsible for the analysis and design of the structural support of adjacent residences and roadway. SAI designed a 22-foot diameter access shaft to allow the equipment needed to conduct the repair work to be lowered down to the drainage tunnel. SAI personnel were on-site during the sheet pile driving and installation of the access shaft.


SAI designed the permanent repair for the storm drain which involved installing a 9-foot diameter steel tunnel liner inside the existing storm drain with grouted annular space and hydraulically applied concrete interior surface. SAI analyzed and designed the tunnel liner and a smaller permanent access shaft with a removable concrete roof under the repaired roadway. SAI determined the limits of the permanent repair and performed the post construction inspection of the storm drain. SAI also inspected an additional 1,500 feet of the storm drain to identify any additional areas of deterioration in need of repair.

Columbia, Maryland

7055 Samuel Morse Drive
Suite 100
Columbia, MD 21046
Phone: 443-741-3500
Fax: 443-741-3700

Baltimore, Maryland
300 East Lombard Street
Suite 840
Baltimore, MD 21202

Phone: 443-741-3500
Fax: 443-741-3700

Baltimore, Maryland
1502 Joh Avenue
Suite 100
Baltimore, MD 21227

Phone: 410-536-3653
Fax: 410-536-3654

Washington, D.C.

100 M Street SE
Suite 550
Washington, DC 20003

Phone: 202-570-7080
Fax: 202-697-5007

Vienna, Virginia

8150 Leesburg Pike
Suite 630
Vienna, VA 22182

Phone: 703-942-8990


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