The 252 in. dia. concrete pipe is used in siphons to convey water in the Central Arizona Project and is the largest diameter pipe in the world. The pipes have a 19.625 in. thick concrete core and two prestressing wire wraps. Using electromagnetic testing techniques, several noncylinder prestressed concrete water conveyance pipes were identified to have broken prestressing wires. SGH evaluated the failure risk resulting from the loss of prestress, determined pipe repair priorities, and subsequently designed post-tensioning repairs and safe excavation for the repair pipe.