Many existing spillways in Sweden are now refurbished for higher discharge capacity than originally constructed for, which calls for improved energy dissipation functions to reduce downstream impacts. The spillway examined belongs to this category, with an increase in design flood by nearly 45%. To attain effective energy dissipation and curtail scouring potential in the tailwater, a new stilling basin is excavated immediately downstream of the spillway piers. Acting as roughness elements, cross-sectional bottom ribs covering the whole width are added to the chute. The element width and height chosen are 0.50 and 0.40 m. Both hydraulic model tests and CFD simulations are performed to explore and optimize the chute flow conditions and assist in the engineering solution. Upon project completion, spillway flood release has seen satisfactory energy dissipation results.