Pulaski 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).

 

CONSTRUCTION IN KARST AREAS

 

   A large sinkhole along Highway 27 near Somerset, is approximately 50 feet in diameter.

   Sinkholes found near any construction project, whether industrial or residential, must be

   carefully considered and require special management.  

 

   This is one of several entrances to Sloans Valley Cave in southern Pulaski County.

   There are many caves in Pulaski County which are part of a complex underground

   drainage system typical of well-developed karst geology.

 

   Excavation of large limestone blocks near the southwestern abutment construction

   site of the new Highway 90 bridge over the Cumberland River near Bronston.

 

    Short Creek, near Stab, Kentucky. This is one of the best examples of a "karst window" in Kentucky,

   where a section of an underground river is exposed at the surface. 

 

   Typical karst geology indicated by highly weathered limestone at the soil-bedrock

   interface on the new Somerset bypass near the intersection of Highway 80.

 

  A large inactive landfill near Sloans Valley in southern Pulaski County. Locating landfills

  in a karst geology setting (sinkholes, springs, caves and underground streams) requires

  very careful planning. 

 

 

    Keno Bridge, near the southern tip of Pulaski County on Highway 751, spans a rail-

    road cut of Pennsylvanian-aged rocks (sandstones and shales) and Mississippian-

    aged rocks (shales and limestones).

 

 

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 represent seismic activity that occurred several million years ago at the latest. There has been no activity along these faults in recorded history. Seismic risk associated with these faults is very low. 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.

 

GROUNDWATER

 

Limestone and siltstone are the prominent rock types found in the western two-thirds of Pulaski County. About three-fourths of the wells drilled in western Pulaski County yield enough water for a domestic supply, with some yields greater than 50 gpm for wells penetrating large solution

openings in karst areas. In the low-lying areas in western Pulaski County only a few wells yield enough water for a domestic supply, except in a few lowland areas near Cumberland River, where yields are sufficient for domestic supplies.

 

In the eastern third of the county, the geology changes to sandstone and shales. Less than half of the wells drilled in the eastern end of the county will produce enough water for a domestic supply. In low-lying areas bordering streams very few wells yield enough water for a domestic supply except in the limited area south of Burnside, where most wells are adequate for a domestic supply, especially from wells that penetrate large solution channels within the limestone bedrock.

 

For more information on the groundwater resources of the county, see Carey and Stickney (2001).

 

RESOURCES

 

  John Sherman Cooper Power Plant is located on the Cumberland River near Burnside.

  This plant uses over 600,000 tons of coal per year, with sources in eastern Kentucky

  and Tennessee.

 

   The Nancy oil field in Pulaski County was developed in the mid to late 1980's, primarily

   from the Knox Formation, at depths of around 1900 feet. Many of these wells produced

   hundreds of barrels per day in initial production, but most (including Zimmerman #2

   shown here) are now producing a few barrels per day on timers.

 

   This highwall in a limestone quarry near Shopville shows the variability of rock types

    within a single formation (Slade Formation).  Dolomite, limestone and shale layers

    are visible. 

 

RADON

 

Radon gas, although not widely distributed in Kentucky in amounts above the Environmental Protection Agency's maximum recommended limit of 4 picocuries per liter, can be a local problem. The limestone, dolomite, shale unit in Pulaski County may contain high levels of uranium or radium, parent materials for radon gas. This unit and several other limestones in the state locally contain the phosphate mineral apatite. Uranium is sometimes part of the apatite structure, and when the limestone weathers away the phosphates containing uranium become concentrated in the soil and ultimately can give rise to high levels of radon. Homes in these areas should be tested for radon, but the homeowner should keep in mind that the health threat results from relatively high levels of exposure over long periods of time, and the remedy may simply be additional ventilation of the home. 

 

 

 

 

 

.