Granite Rip Rap. $103.00/Ton Click to Enlarge. Our Rip Rap is a large granite rock that can be used for drainage. It offers slope protection in creeks, rivers, ditched, shorelines from erosion. "USES: Rip Rap is a large granite rock. It can be used for drainage, creeks, rivers, ditches, shorelines, and slope protection. Also used for erosion ...