An Emergency Design Approach for Immediate Rehabilitation of 4 mi of a Critical 20-in. Water Transmission Main

The Brock Bridge Road Water Transmission Main is a 17,600 LF (3.33 mi) 20-in. ductile iron water main constructed in the 1990s which is the sole water supply for over 30,000 residents within the Maryland City community of Anne Arundel County, MD. Recent corrosion-related failures resulted in long-duration water outages prompting the County to develop a holistic assessment and comprehensive emergency rehabilitation approach. The primary goal of the assessment was to evaluate the condition of the main to develop an immediate rehabilitation approach. Phase I comprised of installing 3,000 LF of temporary 12-in. HDPE water main to provide bypass in the event of successive failures on the 20-in. transmission main. Phase II was comprised of open-trench excavating 3,200 LF of 20-in. Ductile Iron Pipeline (DIP) with Polyvinyl Chloride (PVC) C900. Phase III was comprised of the replacement of an additional 1,100 LF of 20-in. DIP with PVC and the Cured-in-Place-Pipe lining of over 5,200 LF of 20-in. water main. This case study presents a milestone update and lessons learned of the successes and challenges throughout the emergency assessment and design of over 3 mi of critical transmission main.