The Flow Below
In February of 2013, as part of LFI’s ongoing professional training and development program, the LFI staff was provided a technical presentation by Mr. Joseph Ray, a certified Professional Geologist and published author of many papers dealing with dye tracing and subsurface flow. A renowned karst specialist, Mr. Ray provided information on the flow of groundwater below actively running rivers – water features typically considered natural barriers to subsurface flow.
Kentucky features one of the most famous karst areas in the world, and much of the State’s manufacturing base overlies it. Karst environments are well known for topographic features such as sinking streams, caves, and springs. In areas of well-developed karst, such as the Mammoth Cave area, subsurface flow is considered the norm and surface water streams and rivers are rare.
Geologists and engineers are routinely taught that water will flow downhill to join a river or stream at the surface, even when that water flows underground. Conventional wisdom is that the river will act as a natural barrier – the stopping point where groundwater flow becomes surface water flow. The only rule with karst though, is that normal rules just don’t apply. Failure to understand and property interpret subsurface flow can lead to significant errors in determining where contamination may be going, and how much it’s going to cost to clean it up.
Mr. Ray presented compelling evidence that the flow of groundwater through fractured rock beneath overlying rivers and streams is more commonplace than has been historically believed. Pathways of preferential flow make it possible for water to disappear underground for a distance, only to appear again later as a spring. These subsurface pathways are not connected to flow at the surface however, making it possible for the water sink and the spring to be on opposite sides of the river.
Karst environments with fractured rock flow occur in varying degrees in all the states surrounding Kentucky. Mr. Ray emphasized that geologic knowledge of such features is important, as is the ability to apply that information to a given situation. He provided an example of a city in Kentucky where a municipal water supply at a spring turned out to be originating from a water sink just downhill from the city’s sewage treatment plant.
Following his presentation, Mr. Ray entertained several questions from LFI staff. Mr. Ray’s presentation is one of several technical lectures and training sessions in which LFI staff will participate in 2013. Training and continuing education are a part of life at LFI, and a cornerstone in producing exceptional work for our clients.