The Ohio Department of Transportation (ODOT) and Kentucky Transportation Cabinet (KYTC) commissioned the Brent Spence Bridge (BSB) Corridor Project which will transform an eight-mile portion of the Interstate-71/Interstate-75 (I-71/75) corridor and add a companion bridge across the Ohio River adjacent and west of the existing Brent Spence Bridge. The roadway improvements will impact the existing storm, water, and combined sewer systems throughout the corridor and flood protection for the City of Covington, KY. Gresham Smith has led the design of new water, storm, and combined sewer infrastructure in Northern Kentucky, for the Kentucky Transportation Cabinet (KYTC), Sanitation District No. 1 of Northern Kentucky (SD1) and Northern Kentucky Water District (NKWD), and a replacement water transmission main for Greater Cincinnati Water Works (GCWW). Based on the commitment to separate all interstate runoff in the BSB corridor from the existing combined sewer system, GS proposed a separate stormwater trunkline to collect not only the I-75/71 runoff but also areas where stormwater can be routed into the stormwater trunkline from either existing detention basins or infrastructure that was separated by previous projects. The stormwater trunkline will convey flow from approximately 597 acres to the existing Willow Run Flood Pump Station. The expansion of I-75/71 will require an additional 25-30 ft. of fill over portions of the trunk sewer. Due to the significant construction cost and schedule constraints on relocation of a 120-in trunk sewer, GS recommended rehabilitation of the existing Willow Run trunkline and a dry weather diversion sewer. GS performed modeling to ensure that the proposed lining of the existing sewers did not increase the number of combined sewer overflows or the total volume of overflows. To mitigate the loss of Flood Pump Station storage in Covington’s Goebel Park and eliminate the need for expansion of an over 150 MGD Flood Pump Station protecting Covington, KY due to additional stormwater flows, GS design a dual siphon pipe option to discharge flows over the level system protecting Covington from the Ohio River. This two-pipe system would allow for a pressure pipe to convey flows above elevation 512 ft (The height of the levee). The second, smaller pipe was designed to carry water to the Ohio River via the Willow Run Flood Pump Station. Utility conflicts were evaluated by GS throughout the footprint of the expansion of I-75/I-71. This included coordinating with gas, fiber, and electric utilities in addition to highway and roadway improvement to eliminate conflicts with water and sewer structure in Northern Kentucky. Whenever conflicts were unavoidable, GS planned the relocation of water and sewer lines. To address highway expansion and grading changes on the Ohio side of the River, GS designed a relocation of an existing 36 in. water transmission main to a 42 in. transmission that crosses I-75 and connects water service between the west side of Cincinnati with downtown Cincinnati.