The Carbonate Rock Area identifies portions of the Highlands Area
underlain by carbonate bedrock or known to contain karst topography.
Solution (by water) of carbonate rocks such as limestone and dolomite
by surface water or groundwater can cause surface depressions and
development of irregular, subsurface rock topography known as karst.
These conditions make such areas unstable and susceptible to subsidence
and surface collapse. Karst conditions can lead to formation of sinkholes,
sinking streams, enlarged bedrock fractures, caves and underground
streams. Sinkholes function as funnels, directing surface water runoff
into karst aquifers with little or no attenuation of transported contaminants.
Stormwater basins, septic system leach fields, sewers, agricultural
runoff, lawn runoff, underground pipelines, and soil disturbance all
can contribute contaminants directly to groundwater through karst
features. Soils in sinkhole bottoms may be thin or nonexistent. In
addition to potential for groundwater contamination, karst features
present a threat to public safety. Sinkholes and other karst formations
can undermine buildings and structures, including infrastructure facilities,
such as roads, natural gas lines, water supply and sewer lines, septic
systems and stormwater basins.