As a specialist in the evaluation of riprap and armor stone and in the petrographic analysis of concrete aggregates, drill core, riprap, and forensic evaluation of hardened concrete, D A Lienhart is the developer of the "systems approach" in the determination of "true rock quality" for riprap and armor stone. In the performance of petrographic evaluations, David Lienhart uses all of the many petrographic techniques including standardized thin sections and the universal stage in the measurement of optical properties and identification of minerals. Although David Lienhart's specialty through graduate level education is petrography/optical mineralogy, through additional education at MIT, Univ. of IL, Univ. of TX and University of Cincinnati (Department of Army Fellow), Mr. Lienhart also developed a second specialty in the geological engineering field of rock mechanics. The combination of these specialties has enabled him to develop his expertise in the prediction of behavior of rock under various climatic conditions.

David Lienhart’s diverse career has led him through many aspects of geology and engineering. Early in his career he performed research studies on the effects of ultra-high vacuum on rocks and minerals. He assisted with the development of a portable rock drill for obtaining lunar samples with the lunar vehicle and with the development of a lunar soil simulant for pre-lunar landing investigations. He participated in a study to develop a special lubricant for movement of the rocket tractor crawler at NASA’s Cape Kennedy and came up with a source of rounded quartz gravel, which allows the rocket tractor to easily maneuver on its traverse from the rocket storage shed to the launch pad. He performed field studies for the foundations of specialized buildings at the Oak Ridge National Laboratory, loging and developing 3D plots of the foundation rock and it’s conditions. He participated in the Joint US-Canada study of the fracture system in the rock at Niagara Falls in the late 1960s. As part of the foundation studies for proposed Air Force landing fields, he performed clay mineral analyses on soils from all over the world using x-ray diffraction methodology developed by Dorothy Carroll. He studied nuclear radiology safety techniques at the US Army Chemical School at Ft. McClellan and served as one of the twelve Division Radiological Safety Officers for the US Corps of Engineers.

In August of 1974, David Lienhart produced an internal for the Huntington District of the Corps of Engineers on the results of his studies on the deterioration of the concrete linings of the outlet tunnels at Piedmont and Clendening Lakes in eastern Ohio. Using special x-ray diffraction and chemical analyses along with petrographic analyses, he was able to show that the deterioration of the concrete linings of these outlet tunnels were attacked by sulfate-reducing and sulfide-oxidizing bacteria which resulted in the production of H2S gas and H2SO4, This in turn resulted in the concrete being altered to gypsum (CaSO4 • 2H2O), which is soluble in water. Three years after the production of the results of this research, his findings were published in a separate report produced by another research lab. He was given no credit for his research that led to a summarization of his work in the second report.

David Lienhart performed numerous rock mechanics studies on the foundations of many of the high-lift navigation dam and locks of the Ohio River and its tributaries, for dams in New York and Maryland, for Snell Locks on the St. Lawrence Seaway, for the Sault Ste. Marie (Soo) Locks and for numerous other projects. He designed and built his own stress-controlled/strain-controlled rock direct shear device, the design of which he eventually sold to a private firm.

David Lienhart served on numerous dam safety teams inspecting numerous projects throughout the Ohio River Basin for geologic-related safety hazards.

In 1993 he performed a special hydrogeology study of the groundwater conditions at the Fernald Super-Fund Site in support of the Department of Justice with their involvement of an $11 Million lawsuit. He also served as special consultant to the Department of Justice during the trial. For this work he received a Department of Army Medal of Civilian Achievement and the Federal Scientist of the year award for the greater Cincinnati area federal agencies.

In June of 1996, David Lienhart was hired by an Insurance company to investigate a subdivision landslide in a subdivision of homes exceeding ½ million dollars in value. The scarp of the slide extended for over 1200 feet and caused severe damage to several of the homes. A few homes had to be abandoned and the owners were not allowed to retrieve the contents of the homes. The cause of the landslide was due to a creek cutting through glacial till exposing a thick layer of glacial lake clays being squeezed out like toothpaste once exposed by the creek.

Since 1995 David Lienhart has worked for numerous private companies and public agencies investigating the quality of stone for various types of engineering and construction purposes. His work has taken him throughout North America and into the Caribbean. He has lectured at the University of Warwick in the UK and served as an international reviewer for geological and geotechnical engineering publications. Requests for his services have come from Europe and South America.

David A. Lienhart was named ". . the U.S. armourstone expert. . ." by the Geoscientist magazine of the Geological Society of London (January 1997). He served as a consultant on riprap and armor stone to various Corps of Engineers district offices during his 30 years with the Corps. Between 1995 and 2000 he was employed as a partner/sole geologist with Rock Products Consultants. In the year 2000 he formed his own consulting service. His papers on riprap and armor stone have been published by ASCE, ASTM, AEG, GS (of London), Wiley Publishing and A.A. Balkema Publishing. Mr. Lienhart is a Fellow of GSA and GS (of London) and a member of SEPM (Society for Sedimentary Geology), ASTM, AEEG, ASCE, Kentucky Society of Professional Geologists, International Society for Rock Mechanics, American Rock Mechanics Association, American Shore & Beach Preservation Society, American Association for Advancement of Science (AAAS) and is a registered professional geologist in IN and NC. In 2001 he was promoted to the grade of Chartered Geologist and in 2005 he was promoted to Chartered Scientist by the Geological Society (of London).