To increase capacity and maximize mobility, PACLAND designed improvements to the Interstate-5 southbound on/off ramps at the Trosper Road interchange in Tumwater, Washington. Improvements included widening of the off-ramp to three lanes, reconstruction of the southbound loop on-ramp, street lighting design, pavement marking and signing, and traffic signal modifications at the intersection. In the existing condition, the interchange had no water quality or quantity facilities. This project constructed an infiltration pond with pre-settling basin and a media filter drain to provide water quality for stormwater runoff from the loop ramp. PACLAND coordinated with both WSDOT and the City of Tumwater for approval of the project.