Landslides in Greater Cincinnati?
Are you kidding me? What landslides? I know….. you’re talking about the mudslides along Columbia Parkway!
Tim Agnello, Realtor® and Engineering Geologist
Mud slides above Columbia Parkway are a small part of the landslide problem in Greater Cincinnati. The landslides that drop mud and debris onto Columbia Parkway are for the most part shallow landslides that are more of a nuisance, because the City of Cincinnati has to clean up the mud. It makes for sensationalistic news reporting. More damaging and a ubiquitous problem through out the tristate region of southern Ohio, northern Kentucky, and south eastern Indiana are the deep seated landslides damaging roadways and residential housing.
The economic impact from landslide damage is significant on the tristate economy. While the roadway embankments usually get stabilized at the cost of the taxpayer, landslides that damage homes usually end up being condemned because of the economics (very costly to stabilize) and are often a huge financial loss for the property owner. Sometimes the more expensive homes can be repaired, like ib areas such as Mt. Adams where the cost of stabilization is economically feasible.
Landslides are prevalent throughout the tristate area and a 1982 map by the United States Geological Survey shows an area up and down the Ohio River, southern Ohio, northern Kentucky and southeastern Indiana, as having the highest landslide incidence in the U.S. Additionally an early 1980’s study showed Hamilton County, Ohio as having one of the highest per capita costs in the U.S. for repair to landslide damage and this figure excluded the landslide damage caused by the Mt. Adams landslide in the late 1970’s. In Mt. Adams, a seven foot high braced vertical cut in the hillside for the I-471 cloverleaf started the ground moving 600 feet up slope causing millions of dollars in damage to housing and roadways. At the time this was one of the costliest landslides in U.S. history becaues of the high dollar real estate impacted.
Landsliding is prevelant through out the tri-state and in 1996, a very wet year, a local engineer polled his fellow engineers and found that they were working on over $10,000,000 in landslide repairs through out Hamilton County. Landsliding is such a problem that the City of Cincinnati in the early 1980’s created an overlay zoning map called the Hillside Environmental Quality District (EQD) to partially reflect the area that had a high probability of sliding. The City has recently revised and expanded upon the EQD, which is now called the Hillside Overlay District. Further as a result of a report to the Smale commission from the Geology Department at the University of Cincinnati an Engineering Geologist (a specialist who works in and applies geology to civil engineering projects including housing, roadways, etc.) was appointed to oversee projects with in the City of Cincinnati limits to help curtail damages. Outside the political boundaries of the City of Cincinnati there exists no comparable zoning overlay or geologist to monitor construction.
The underlying geology of Hamilton County also underlies a substantial area of the tri-state region (including Boone, Campbell, and Kenton County, Kentucky; Dearborn, Ohio, and Switzerland County, Indiana; and Hamilton and Clermont County, Ohio) and is subject to landsliding (there are other problems). The soil (earth/clay) that is subject to slippage is derived from a shale rich flat lying bedrock called the Kope formation. The Kope is over 200 feet thick and when exposed to air and water breaks down rapidly into its clay minerals and clay size particles. The Kope bedrock itself is stable ground and often in landslide prone areas the sub foundation work is “socketed” into the Kope bedrock to give the building a stable foundation base. It is the weathering of the Kope shale, which is seldom exposed naturally (because of high shale/clay content) except when exposed in human engineered cuts (for instance the area behind Beechmont levy mall, I-75 cut in the hill in Kentucky), that breaks down to make our unstable hillsides.
Geologist and engineers call the soil profile that develops on hillsides over the top of the Kope bedrock colluvium. It is this colluvium that has a high propensity to slide when moved by human activity or in some instances undercut by stream erosion. The colluvium on the tri-state hillsides is anywhere from a couple of feet thick near the top of the hill slope to sixty to seventy feet thick near the base. Hence the massive retaining wall at the base of the Mt Adams hillside that was necessary to stabilize a landslide that was sixty+ feet deep. Today the Mt. Adams hillside is being re-developed again, to understand the problem, all you have to do is look up and see all the fairly new retaining walls and foundation piers that are exposed to hold the hillside back and give a stable base for housing being developed. Think about it; is the Mt. Adams hillside any different then the rest of our hillsides? Geologically the answer is no.
Greater Cincinnati’s legacy of landsliding is one of repeated efforts to construct roadways and housing on the surrounding hill slopes, followed by landsliding, and abandonment of the housing project ultimately leading back to the green hillsides you see today. If you question whether this could happen today, please don’t hesitate to call me so I can tell you where you might find some new construction with costly repairs or landslides that every year are working there way closer to the next unsuspecting victim.
Still not quite convinced?
Don’t worry, you are not alone, there are lots of citizens and professionals that are not fully aware of the potential for and extent of landsliding in the tri-state region. For example, I once explained to a fellow real estate broker that Hamilton County, Ohio had one of the highest costs per capita in the U.S. for repair to landslide damage. Her reply was “I don’t believe that for a second.” Further, a colleague in geology once told me that years ago he walked across a rather large landslide with one of the top pros (non geologist) in Greater Cincinnati. This pro was unaware that he was walking across an active subdued old landslide! There are plenty of cases where engineers and geologists did not recognize the preexisting old landslide feature adjacent to their home! Buyer beware, as landslide recognition is a specialty with in the field of geology! Workshops we are offering now and in the future will address the topic of landslide recognition and awareness. If you are interested in reading further, below are some articles on landsliding in Greater Cincinnati:
Historic Rock Quarries and Modern Landslides in Price Hill, Cincinnati, Ohio
Cover story in Ohio Geology magazine, 2005, No. 2. published by the Ohio Department of Natural Resources.
“Numerous small rock quarries existed on the hillsides of Cincinnati in the 1800s and early 1900s when one of the nation’s most rapidly growing cities had a tremendous need for the local building stone. Now these historic quarries can be directly associated with modern-day landslide problems.” Click here to read the complete article.
Residential Lot Development and Landsliding on the Cincinnati Hillsides
Landsliding in Lower Price Hill, Cincinnati. Originally published in The Hillside Trust Outlook, March 2003.
“The Price Hill hillside area today can best be categorized as predominately green space. However, the ‘green’ character of the hillside masks numerous failed early attempts to develop the ‘natural’ hillside.” Click here to read the complete article.
Road Building and Landsliding on the Cincinnati Hillsides
Originally published in The Hillside Trust Outlook, Winter 2003.
“The Mill Creek and Ohio River valley walls hemmed in the early settlement of Cincinnati. Shortly after the settlement of Cincinnati in 1788 crude earthen roads were cleared and constructed up the hillside.” Click here to read the complete article.
Sliding into Cincinnati
Featured in the August 2002 Issue of GeoSpatial Solutions magazine for the Top Apps 2002 International Brainiacs contest.
“Cincinnati has one of the highest costs per capita in the United States for landslide damages. Therefore, in September 1999, the city’s engineering geologist referred me to a hill slope particularly prone to landslides to map its geology and features. ” Click here to read the complete article.
Landslide Terrain Analysis Of A Spatially And Temporally Human Influenced Hillslope
Scientific abstract by Tim Agnello. Presentation given at the Geological Society of America in Denver, Colorado in 2002.
“Historic quarry operations, deforestation, clear cutting, grading for housing (both historic and ongoing), road construction, loading of the slope from dumping (landfill, construction debris, etc), and modification of the natural hydrology have set the stage for past and ongoing destabilization of the hillside.” Click here to read the abstract.