travel quite rapidly through these underground networks - up to several miles a day - and contaminants can be transmitted quickly to wells and springs in the vicinity.

Groundwater

• Groundwater is an important source of private and public water supplies. However, everyday activities in the source area can contaminate the groundwater on which so many people depend for everyday use. The source area is the land surface that contributes water to an aquifer. It is very important to protect these source

areas from detrimental activities.

Watersheds

• A watershed is an area of land from which all water drains into a common water body. Rainfall, spring runoff, and groundwater drain from upland areas to a low point or basin, usually a larger stream, river, lake, or bay.

• Water enters a karst watershed through both direct and indirect means. Precipitation in the form of rain and snow, which is usually the greatest during January through May, enters the aquifer directly as surface runoff or

3 Menu

What is Karst?

• Karst is defined as a landscape with sinkholes, springs, and streams that sink into subsurface caverns. The word "karst" was developed in Europe, where early geologists first studied the nature of groundwater flowing through limestone hills and valleys.

KARST

A land area that includes sinkholes, springs, sinking streams, and caves.

• Approximately 10% of the earth's surface (and 20% of the U.S.) is composed of karst; however, approximately 25% of the world's population lives on these areas! The hollow nature of karst terrain results in a very high pollution potential. Streams and surface runoff enter sinkholes and caves, and bypass natural filtration through soil and sediment.

• Unless watersheds are protected, these direct connections between the

• Between 570 million and 320 million years ago, the geographic area now occupied by the eastern United

States was predominantly covered by a calm, shallow, tropical sea. The sea was populated by microscopic (and larger) organisms that lived, died, and sank to the bottom of lagoons, or were washed into deeper parts of the basin by storms. Over the eons, the deposits of calcium-rich shells and skeletons solidified into the bedrock that we call limestone (CaCO₃), dolomite (CaMg(CO₃)₂) and gypsum (CaSO₄.2H₂O). These rocks are soluble in dilute acids. Water becomes slightly acidic when it takes up carbon dioxide while passing through decaying organic debris in the surface soils. The

• During the Appalachian Orogeny, a series of mountain-building events in the central and eastern U.S., rocks were alternately buried, uplifted, faulted, folded, and fractured. The geologic stresses of mountain-building and subsequent erosion created cracks and fissures in the rock through which rainwater and groundwater entered and actively dissolved the organic limestone. Within the past 10 million

years, caves, conduits, and underground drainage systems have been dissolved into this rock by moving water. Surface water and streams are captured by underground channels. These channels convey the water to springs which sustain the water flow, cool temperatures, and aquatic habitats of our rivers.

4 Menu

Pollution and Protection of Karst Wells and Springs

resulting in unsafe drinking water supplies for both you and your neighbors. Household wells and springs can be contaminated by many common and seemingly harmless activities such as boarding or pasturing livestock; the over-application of pesticides, herbicides, or fertilizers; storing home heating oil; vehicle maintenance; and on-site sewage disposal.

Protecting Your Well Water

• The best means of protecting your groundwater

supply is to become familiar with the geology and hydrology of your watershed, and to work diligently with your neighbors to clean up dumps and limit potentially polluting activities in key source water areas.

• Most health risks associated with low-level bacterial contaminated groundwater supplies can be resolved at the tap with an individual home treatment system (normally for less than $0.15 per gallon). For rural neighborhoods or subdivisions, community well fields, or springs with permitted package treatment plants are an option. All treatment systems have associated costs and specific maintenance requirements.

• Proper well siting and construction is essential to keep polluted surface water out of the aquifer and to avoid drilling into caves. For the best protection immediately around the well itself, isolate the well as much as possible. Site new wells at least 200 to 1000 feet away from barns, feed lots, livestock pens, sinkholes, dumps, septic systems, fuel tanks, and other above-ground and underground sources of contamination. Fence livestock out of the spring or wellhead area. Maps developed by local cavers and water management districts can also assist in locating wells away from subsurface cave pass on a safe, reliable source of water for drinking, bathing and other needs. Your will is also valuable because it represents a large financial investment.

Your family's health depends on a safe, reliable source of water for drinking, bathing and other needs. Your well is also valuable because it represents a large financial investment.

5 Menu

Water Well Tips

Wells should be lined, or "cased," with welded lengths of steel pipe, which are grouted in place. Since the outside surface of the well casing is a direct conduit to the aquifer the top of the well should be surrounded by a concrete pad and tightly capped, or "sealed."

• Do not spread or store fertilizer, pesticides, petroleum products, or

other chemicals in the zone around the well.

• The wellhead area should be landscaped so that standing water cannot accumulate around the well.

• Never pump a new limestone well at high rates (greater than 200 gallons per minute) unless aquifer tests have

been conducted by a qualified hydrogeologist. In some areas, excessive pumping of karst wells has caused ground subsidence, sinkhole collapses, and de-watering of neighboring wells and ponds.

• Homeowners and prospective home buyers should be aware that water well samples required for new well permits and property transactions may be collected immediately after "shock" chlorination treatment to disinfect the well. Such samples will not reveal the actual concentration of bacteria and other constituents that may be

present after the chlorine is pumped from the system. Re-testing is recommended.

• Abandoned wells, old hand-dug farm wells, and cisterns often represent direct connections between the surface and the karst aquifer. Abandoned wells should be properly plugged with clean rock (in the water zone) and sand-cement grout (to the surface) to prevent runoff from migrating directly to the groundwater. No wastes or debris should ever be disposed in a well or in karst features near any well.

• Test domestic wells for coliform bacteria, nitrates, and other suspected compounds at least annually, and keep a record of these as a "background" for evaluating any future pollution. Also record the dates that muddiness or low water level problems occur, as well as current and previous climatic conditions.

• Well drillers are required to disinfect new wells with chlorine; attempts to use unapproved "cleansers" in this process have contaminated aquifers for great distances.

Local health departments regulate the practice of well abandonment.

. Be sure your driller follows all applicable state permit guidelines for water well construction and development.

• Polluted and low-yielding wells can sometimes be rehabilitated by a skilled driller who can acidify the well; "seal off" a contaminated water zone with casing, packers, and grout; and re-drill the well to a cleaner water zone (if one exists). Consult with your neighbors about the depth and quality of their water wells, as well as local well drillers, the health department, and geologists before attempting to re-drill a water well.

• If contamination is suspected or is a threat, a specific study to map land use patterns and determine the direction and rate of groundwater movement may be necessary. The information from such studies could serve as the basis for long-term, local solutions to pollution. Contact your local health department or state environmental agency for the names of environmental consultants, non-profit organizations, universities, or watershed groups with experience in this area.

6 Menu

Sinkhole Management

• Sinkholes are natural drainage points for our groundwater system, so they should never be filled. If a sinkhole is plugged, water will not drain properly, may run off onto adjacent property, and possibly may cause flooding, subsidence, erosion, and pollution. The downstream springs, caves, wells, and streams which receive water from the sinkhole should be identified.

• If collapsed sinkholes present a hazard to health and safety, and structures, they often can be stabilized in a way that maintains natural drainage abilities.

• Always contact a geologist or engineer experienced in sinkhole repair before attempting to backfill or "seal" a sinkhole.

• Do not locate a septic system, feed lot, animal waste lagoon, or storm water basin, near known or suspected sinkholes or caves. If sinkholes appear near such sources of bacterial contamination, use appropriate methods to prevent runoff from these areas from entering the sinkholes. Minimize unnatural or increased drainage into sinkholes.

• Do not apply any fertilizer, pesticides, or other chemicals within at least 100 feet of a sinkhole. Notify your contractor of the location of all sinkholes.

• If you purchase property where trash has already been dumped in sinkholes, consider cleaning them out and restoring vegetation to improve water quality. Check with your local Natural Resources Conservation Service (NRCS) office, Soil and Water Conservation District, utility district, state conservation agency, or US Fish and Wildlife Service office. These groups sometimes have funding to assist

with the cost of trash removal in certain watersheds. Volunteer labor and equipment also can be a big help. Contact local cave clubs and the county litter control officer for support. County public service authorities will sometimes waive the landfill tipping fee for waste materials collected in sinkhole dump clean-ups.

• Contact the above agencies for help with these recommendations.

How does this affect my drinking water?

Contaminants entering the groundwater system through sinkholes present a significant health concern, because many wells tap water-filled cavities that are directly connected to the surface. In karstlands, groundwater usually resurfaces at spring and therefore carries the contamination into streams and rivers that also may be used as water supplies.

7 Menu

Sinkhole Management Protects Property Values

streams, which disappear underground. Both circumstances have one thing in common: caves and/or broken, weathered limestone bedrock near the soil surface. Over 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 the soil.

Management Methods

• 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 and wells.

• 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.