Sinkhole Management Protects Property Values
are natural depressions in the landscape caused by solution
and subsidence of earth materials.
Sinkholes are common throughout about one-quarter of the
U.S. Generally sinkholes can be recognized as circular or oval
depressions in cultivated fields that may or may not pond standing
rain events. Sinkholes can also have open bottoms, swallowing entire
streams, which disappear underground. Both circumstances have one thing
in common: caves and/or broken, weathered limestone bedrock near the
thousands of years, flowing groundwater gradually dissolved channels through
the limestone. This process created underground caverns of various sizes
which can not always support the weight of overlying soil and rock.
A sinkhole is created
when the surface materials collapse or are dissolved into the underground
cavern or cave stream.
- Surface water or irrigation runoff can wash soil sediment,
fertilizers, animal waste, bacteria, and agricultural chemicals
into the groundwater below.
In sinkholes with open or rocky bottoms, this bypasses the natural filtration
and biochemical breakdown processes that occur as water percolates through
- If you have sinkholes or caves on your property, help prevent
excessive runoff from
entering groundwater by planting a vegetative barrier and/or fencing
around the sinkhole.
- Avoid structures that divert water naturally flowing into sinkholes.
Soil-lined diversion ditches often collapse when storm water
erodes through to caves and underground cavities.
- The size and shape of the
vegetated zone needed will depend on the slope of
the land and the distance from the disturbed area. A 100-foot-wide grass
filter strip is ideal; a 50-foot strip is still helpful; and grass
strips even as
narrow as 13 feet can trap enough sediment to be effective. Filter strips
will remove sediment only from shallow, sheet-type flows; they
are less effective
in deeper, rapidly flowing water, such as in gullies or ravines.
- Leave a wide
natural buffer of trees and under story vegetation around sinkholes
and caves when clearing land, harvesting timber, or
disturbing ground in the drainage area.
- Never dump trash, dead animals,
or debris into sinkholes. This is illegal in most areas because
it can directly and rapidly funnel leachate to springs
- Immediately after disturbing any soil, lightly fertilize, seed,
and mulch the area to control erosion. A geotextile may be needed on
very steep slopes. Water the area frequently until grass seed
germinates. To protect embankments and channels until grass is
established, build secure silt fences out of mesh plastic, anchored to
the soil, and staked to hay bales.