Hardin County, Kentucky

 

KARST HAZARDS

 

 

Never use sinkholes as dumps. All waste, but especially pesticides, paints, household chemicals, automobile batteries, and used motor oil, should be taken to an appropriate recycling center or landfill.

 

Make sure runoff from parking lots, streets, and other urban areas is routed through a detention basin and sediment trap to filter it before it flows into a sinkhole.

 

Make sure your home septic system is working properly and that it's not discharging sewage into a crevice or sinkhole.

 

Keep cattle and other livestock out of sinkholes and sinking streams. There are other methods of providing water to livestock.

 

See to it that sinkholes near or in crop fields are bordered with trees, shrubs, or grass "buffer strips." This will filter runoff flowing into sinkholes and also keep tilled areas away from sinkholes.

 

Construct waste-holding lagoons in karst areas carefully, to prevent the bottom of the lagoon from collapsing, which would result in a catastrophic emptying of waste into the groundwater.

 

If required, develop a groundwater protection plan (410KAR5:037) or an agricultural waterquality plan (KRS224.71) for your land use.

 

(From Currens, 2001)

 

 

About karst

More about karst

 

DRAINAGE AND SUBSIDENCE

 

 

Limestone terrain can be subject to subsidence hazards, which usually can be overcome by prior planning and site evaluation. "A" shows construction above an open cavern, which later collapses. This is one of the most difficult situations to detect, and the possibility of this situation beneath a structure warrants insurance protection for homes built on karst terrain.

 

In "B," a heavy structure presumed to lie above solid bedrock actually is partially supported on soft, residual clay soils that subside gradually, resulting in damage to the structure. This occurs where inadequate site evaluation can be traced to lack of geophysical studies and inadequate core sampling.

 

"C" and "D" show the close relationship between hydrology and subsidence hazards in limestone terrain. In "C," the house is situated on porous fill (light shading) at a site where surface and groundwater drainage move supporting soil (darker shading) into voids in limestone (blocks) below. The natural process is then accelerated by infiltration through fill around the home.

 

"D" shows a karst site where normal rainfall is absorbed by subsurface conduits, but water from infrequent heavy storms cannot be carried away quickly enough to prevent flooding of

low-lying areas.

 

Adapted from AIPG (1993).

 

Alluvial areas may be subject to flooding. For information on flooding in the county, contact the Floodplain Management Branch, Kentucky

Division of Water, 502.564.3410.

 

CONSTRUCTION IN KARST AREAS

 

 

Karst geology (sinkholes, underground streams, springs and caves) is prevalent in Hardin County. This is an example of a "cover collapse sinkhole" where an opening to a sinkhole has developed when the soil plug to the sinkhole collapsed. It has been filled with rocks to allow drainage.

 

POND CONSTRUCTION

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Successful pond construction must prevent water from seeping through structured soils into limestone solution channels below. A compacted clay liner, or artificial liner, may prevent pond failure. Getting the basin filled with water as soon as possible after construction prevents drying and cracking, and possible leakage, of the clayey soil liner. Ponds constructed in dry weather are more apt to leak than ponds constructed in wet weather. Illustration by Paul Howell, U.S. Department of AgricultureóNatural Resource Conservation Management.

 

†† A clayey-soil pond liner is placed in loose, moist layers and compacted with a sheepsfoot roller. A geotechnical engineer or geologist should be consulted regarding the requirements of a specific site. Other leakage prevention measures include synthetic liners, bentonite, and asphaltic emulsions. The U.S. Department of Agriculture-Natural Resources Conservation Service can provide guidance on the application of these liners to new construction, and for treatment of existing leaking ponds. Photo by Paul Howell, U.S. Department of Agriculture-Natural Resources Conservation Service.

 

Dams should be constructed of compacted clayey soils at slopes flatter than 3 units horizontal to 1 unit vertical. Ponds with dam heights exceeding 25 feet, or pond volumes exceeding 50 acre-feet, require permits. Contact the Kentucky Division of Water, 14 Reilly Rd., Frankfort, KY 40601, telephone: 502.564.3410.

 

 

RESOURCES

 

†† Much of Hardin County obtains water from severalsprings on the Nolin River and the headwaters of Rough River. This picture shows the water intake equipment for Hardin County Water District #2 at White Mills spring in southwestern Hardin County.

 

††††† †††††††††Pirtle Spring supplies much of the raw water for Hardin County Water District #1.

 

 

GROUNDWATER

 

In karst areas, such as Hardin County, stormwater runoff can flow underground through large solution channels. This groundwater flow does not follow the topography of the surface, and water from one watershed may flow underground and reappear in an adjacent watershed. A knowledge of the groundwater flow, gained through dye-trace studies, is required to manage storm water and to protect water quality and drinking water sources.

 

Delineation of source water protection areas is the process of defining the area of land in which activities are likely to impact the quality of the drinking water source. For more information, see http://kgs.uky.edu/kgsweb/download/misc/swapp.pdf

 

In northern Hardin County nearly all drilled wells in the alluvium of the Ohio River valley are adequate for domestic use, with many wells yielding several hundred gallons per minute (gpm). Compound horizontal wells set in the alluvium may yield 5,000 gpm, which is sufficient for a community or industrial use. In the Rough River lowlands of southwestern Hardin County most drilled wells are adequate for a domestic supply. Depths of drilled wells range from 60 to 300 feet. In much of central, eastern and northern Hardin County, except in the lowlands of the major creeks and rivers, about three-quarters of the wells drilled yield enough water for a domestic supply. In the rest of the county very few wells yield

enough for a domestic supply, except in a few lowland areas bordering streams, where a few wells meet the supply needs for domestic use.

 

Springs with flows ranging from a few gallons per minute to 3,128 gpm are found throughout the county. Many of the springs are of the depression type, and yield more than 100 gpm when pumped. For more about the groundwater resources of the county, see Carey and Stickney (2001).

 

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Freeman Lake in Greenbelt Park (Elizabethtown) was formerly used as a water reservoir for the city.

 

 

TAR SANDS

 

Naturally occurring petroleum can be found in some sandstone outcrops in Hardin County. These are called "tar sands" and occur in the Hardinsburg Sandstone.

 

 

MINERAL RESOURCES

 

A natural cave is exposed in the E-town quarry north of White Mills, which mines limestone from the Ste. Genevieve and St. Louis Formations.

 

 

NATURAL RESOURCES

 

Logging has become a more common activity in Hardin County as woodlands mature. Logging can have serious impact to water quality if Best Management Practices (BMPís) are not followed.

 

 

GEOLOGY

 

Approaching Hardin County from the east on the Bluegrass Parkway, the transition from the Mississippian Plateau physiographic region into the Knobs region is very noticeable.

 

 

 

Rockslides are relatively common in road cuts along the Bluegrass Parkway in Hardin County, and result from freezing and thawing of ice in fractures in the rock.

 

 

MAPPED SURFACE FAULTS

 

Faults are common geologic structures across Kentucky, and have been mapped in many of the Commonwealth's counties. The faults shown on this map are part of the Pennyrile Fault System, which is considered not to be active. However, earthquake damage in Hardin County is still a possibility.Soil creep, slumps, and landslides occurring along steep slopes may occur from erosion or ground motion associated with a strong earthquake.Areas associated with alluvium are subject to liquefaction during a strong earthquake event.

 

Faults may be associated with increased fracturing of bedrock in the immediately adjacent area. This fracturing may influence slope stability and groundwater flow in these limited areas.