Herschel Hall1, Justin James2, Zachary Bloomfield3 1Knoxville Utilities Board, Knoxville, TN 2CDM Smith, Knoxville, TN 3 Garney Construction, Knoxville, TN ABSTRACT: Located in Knoxville, Tennessee, the Neyland Drive Trunkline is the backbone to the Knoxville Utilities Board (KUB) collection system. The reinforced concrete trunkline was installed in 1947 and ranges in size from 72-inches to 84-inches as it enters the Kuwahee Wastewater Treatment Plant. The Average Dry Weather Flow Rate for the trunkline is 18 million gallons per day (MGD), with wet weather flow rates reaching 80 MGD. The project site is located adjacent to the University of Tennessee campus, a large football stadium, and popular basketball/concert venue. In April 2022, a contractor working for KUB conducted a multi sensor inspection of approximately 14,500 linear feet of the Neyland Drive Trunkline. The inspection report indicated that there was significant loss of wall thickness at points throughout the trunkline. In light of this information, KUB quickly embarked on a trunkline rehabilitation project to address the aging reinforced concrete sewer line. The entire trunkline was closed captioned televised (CCTV) to further evaluate the condition of the trunkline. The CCTV did reveal evidence concrete spalling and exposed rebar further confirming the data captured with the multi senor inspection. The manhole structures were also evaluated for defects and need for replacement or rehabilitation. KUB decided to approach the project by partnering with Garney Construction as a Construction Manager at Risk (CMAR). The design engineer, CDM Smith, evaluated design options alongside Garney in a collaborative effort address the issues identified with the trunkline, but at the same time mitigating the known risks presented by a project of this complexity. The presentation will highlight key design and risk elements considered during the design development phase of the project to determine approach. Multiple design alternatives will be reviewed with the associated pros and cons, including construction cost considerations. Lessons learned during the construction phase of the project will be discussed including critical safety factors. In addition, critical success factors for the CMAR approach and implementation will be discussed.