Onken Enterprises, LLC is an Allan Certified Block Retaining Wall Company 

Allan Block Retaining Walls is designed to give contractors the proper training and tools to ensure that top-quality retaining walls are built. It sets the standard for professionals on how to install retaining walls. It is earned after attending an instructional course followed by a written exam that consist of basic principals of wall designs, how Allan Block and geogrid reinforment work together, basic design methodology, why walls fails, and wall estimating tools.