Tri-State Builders has poured retaining walls of all heights and shapes. Some of our finest work has included tapering walls and even curved retaining walls. Let Tri-State Builders help terrace your property or maximize land usage with a poured concrete retaining wall. Tri-State Buildes now offers a unique, cost effective option for retaining walls. Introducing Pre-Cast Retaining Walls. These concrete blocks are set with a crane or excavator and lock together to ensure maximum holding power. They come in different sizes and patterns to amplify curbside appeal.