In Plano, gravity sewer mains, which carry wastewater without pumping, are designed with specific slopes to maintain smooth and continuous flow. According to the City of Plano Utility Design Standards, sewer lines must be sloped to achieve adequate velocities, typically around 2 ft/sec, to prevent sediment buildup, reduce blockages, and avoid system failures. Slope design is coordinated with pipe size and depth to support reliable service connections and future development.