Founded in 1854, Louisville Water is one of the oldest water utilities in the United States and currently supplies water to Metro Louisville and five surrounding counties. Large diameter transmission mains serve as conduits from Louisville Water’s two treatment plants, Crescent Hill Water Treatment Plant and B.E. Payne Water Treatment Plant, safely and reliably providing water to customers west and south and to the 30 MG Cardinal Hill Reservoir. The aging Kentucky-Oak-Glenmary 48-inch cast iron transmission main is critical to maintaining flow and pressure within the expansive water system. Measuring over four miles, this segment runs along Kentucky Street, Oak Street, and Glenmary Avenue, through a densely developed area, and has been in continuous use since the 1890s. Now experiencing increased breaks and leaks, replacing the 130-year-old pipeline has become a priority for Louisville Water. Louisville has been built around the main; neighborhoods, businesses, parks, and crossings such as I-65, CSX railroads, and Beargrass Creek all present significant challenges when considering replacement. Additionally, the pipeline must be in service from early May to early October, to accommodate Louisville Water’s peak demand period. With these constraints in mind, the main replacement was broken into three phases: • Phase 1 (already completed) used sliplining methods with 42-inch steel carrier pipe within the existing 48-inch cast iron. • Phase 2 (currently under construction) uses traditional dig-and-replace methods to satisfy Louisville Water’s requirement to maintain hydraulic capacity. The new ductile iron pipe is being placed in the same location as the existing main. • Phase 3 (not yet under design) traverses some of the densest and busiest neighborhoods in Louisville. This presentation will focus on Phase 2, presenting: critical design and construction elements; collaborative efforts between the Owner, Engineer, and Contractor to optimize schedule to maintain system capacity and minimize neighborhood/traffic disruption; stakeholder engagement and communication strategies; current construction progress and lessons learned thus far. Lessons learned that will be presented include: • Laying the new pipe in the same location as the existing pipe in which many utilities have been installed over and nearby in the past 130 years. • Coordination with the homes and businesses along the route, some that are within 30 feet of the pipe centerline.