WELLHEAD PROTECTION BEST
MANAGEMENT PRACTICES FOR
SMALL FARMS IN THE PACIFIC
There are approximately 12,000 small farms in Idaho, Oregon, and Washington, mostly near large cities and towns. The number of small farms is growing rapidly and may double by the end of the decade. Small farms range in size from 1 to 20 acres. Many small farm owners have horses or other livestock which are fed by intensive management of the farm, often using quantities of fertilizers and chemicals far exceeding quantities used on large scale farms (on a per acre basis).
Small farms can have a significant impact on water quality. Most small farms are concentrated near the larger cities and towns in Idaho, Oregon, and Washington. These farms, or ranchettes, often contain several horses and other livestock. The owner tries to produce all feed for these animals on this small acreage. Thus forage crops are important. Because most small farm owners are relatively affluent and derive most of their income from off-farm sources the cost of chemicals used in the production of forage crops is often not a limiting factor in management. This results in a very high chemical use rate per land unit area.
Large numbers of small farms are appearing in King, Spokane, Pierce, Thurston, and Snohomish counties in Washington; near Portland, Medford, Bend, and in the Willamette and Rouge River valleys in Oregon; near Boise, Coeur d'Alene, and in Canyon county, Idaho. Because of their proximity to urban areas these farms are often situated on or near some of the most sensitive aquifers and surface waters in the Pacific Northwest.
Ninety-five percent of rural residents use groundwater obtained from private wells to supply both drinking water and farm needs. Without an adequate, clean source of groundwater to supply wells many people could not live in rural areas. You should consider a rural well a gold mine -- it gives a person independence. Contaminated drinking water from a well could compromise a person's independence and actually force people off their own land.
The purpose of this slide set is to provide a background that will enable a small landowner to make decisions for wellhead protection utilizing best management practices that will protect the environment.
|1. Title Slide|
This slide set is entitled "Wellhead protection BMPs for small farms in the Pacific Northwest." Funding for the development of this slide set was provided by a grant from the Pollution Prevention Program of EPA Region 10. Owners of small farms and/or large lots who obtain their drinking water from private wells that utilize the best management practices introduced in this slide set will help protect both groundwater and our own health.
Why should I be concerned? In the Pacific Northwest groundwater is our main source of drinking water. In fact, 95% of rural residents use groundwater obtained from private wells to supply both drinking water and farm needs. Your well is your own private gold mine! Improperly constructed and maintained wells can put both your family and the health of pets and/or livestock at risk.
|3. What is Groundwater?|
Groundwater is the underground water found in the cracks of bedrock and in spaces between gravel and sand particles. It does not form an underground lake. Groundwater can occur just a few feet from the surface or may be buried several hundred feet down.
|4. What is an Aquifer?|
Large areas that contain groundwater are called aquifers. Wells are drilled into aquifers. Aquifers are found in many areas of the Pacific Northwest. Remember that water is a finite resource essential to life. Without an aquifer many of you could not live in a rural area. An aquifer and your well give you independence! Contaminated drinking water from your well could compromise your independence and even force you off your landholding.
|5. Multiple Aquifer
Within a given geographic area many farms obtain their drinking water from wells drilled into the same aquifer. In fact, it is not uncommon to find hundreds of rural wells drilled into the same aquifer.
|6. Impact of
Since several wells are on the same aquifer, everyone should be concerned about potential pollution problems. For example, if nitrates on a farm leach into the well water of the farm, it stands to reason that all drinking water wells drilled into the aquifer may be in jeopardy. In this example you can see nitrate moving into the aquifer. Eventually, by the process of diffusion some of the leaked nitrate may end up in a neighbor's well.
|7. Well Water|
The condition of your well and its proximity to contamination sources determine the risk it poses to the quality of your drinking water. Some items that can adversely impact the quality of water produced by your well include: (1) cracked well casings, (2) a pesticide spill near your well, and (3) the proximity to high nitrate sources. The nitrate sources can include commercial fertilizers used on crops, lawns or gardens, and stockpiles of organic materials including manures.
The prevention of well contamination should be your top priority because once contaminated, it becomes very difficult, if not impossible, to clean up the water. Since the water produced from your well comes from the same underground body of water as your neighbor's well, if your well becomes contaminated your neighbor may suffer the same fate.
The purpose of this slide set is to provide you with information that will help reduce the risk of groundwater contamination and at the same time help you improve the condition of your drinking well water. Any practice that will protect or improve our drinking water can be called a best management practice, or BMP. A BMP can be defined as an implemented strategy which can eliminate or minimize the threat of environmental pollution.
|10. Parameters to
There are five major areas where BMP implementation should be considered. These areas include: (1) your well location, (2) well construction, (3) current well management and maintenance, (4) new wells, and (5) unused wells.
|11. Well Location|
Well location is a crucial factor determining the safety of drinking water. You need to consider where the well is in relation to both surface drainage and groundwater flow. Surface drainage is easy to consider. If you prevent surface runoff water moving toward your well you have greatly reduced the potential for well contamination.
This illustration can be used to demonstrate how a well should be located on the landscape. Remember, we do not want surface water runoff to flow toward the well. The left box shows an ideal situation. Here, the well is high in the landscape and all surface water will drain away from the well -- minimizing possible contamination. On the other hand, the well in the right box is poorly located and could be contaminated if pollutants move with surface water runoff toward the well.
Surface topography does not always indicate the flow direction of a pollutant moving in groundwater. Actual groundwater movement depends on the depth of your aquifer. A local hydrologist may be able to provide you with this information.
An important aspect of well location is the concept of separation distance. Many states require minimum separation distances from sources of potential pollution. On small farms potential pollution sources include pesticide and fertilizer storage tanks, manure piles, livestock feeding areas and barnyards, septic tanks and drain fields, and gasoline and fuel oil tanks. If no distances are specified by your state, provide as much separation as possible between the well and any potential contamination source.
|15. Separation of
Since storage laws vary in the Pacific Northwest, this illustration shows the relative distances potential pollutants should be stored away from drinking well water. Note that all potential pollutants are not equal. In this illustration septic tanks can be located relatively close to wells compared to agrichemical tanks and gas tanks. Separation distances are relatively large for liquid animal wastes.
Greater separation distances may be needed depending on well site factors such as soil type and slope. Both factors need consideration when siting a well. You should also consider potential contamination sources on adjacent properties.
Changing the location of your well in relation to contamination sources may protect your water supply, but not the groundwater itself. Any condition likely to cause groundwater contamination should be improved, even if your well is far away from the potential contamination source.
|18. Well Construction|
The second item to consider when trying to improve drinking well water quality is well construction. Proper well design reduces the risk of pollution by sealing the well from anything that might enter it from the surface. Well construction information may be available from the driller, the previous owner, or the well construction report.
|19. Well Construction|
Five items dealing with well construction deserve detailed consideration. These items include: (1) casing and the well cap, (2) casing depth and height, (3) the well age, (4) well type, and (5) well depth. We will consider each item individually.
Casing and the well cap are the first items that should be evaluated. Casing is a steel or plastic pipe installed during well construction to prevent the collapse of the borehole. This illustration shows a cross-section of a typical well. You can see that the well casing is fitted into the borehole.
The space between the casing and sides of the hole should be sealed with grout to prevent pollutants from seeping directly into the well. You should check that there is a seal between the exterior of the casing and the adjoining soil and/or rock material.
|22. Visual Inspection|
Visually inspect your well casing for holes or cracks at the surface. Use a flashlight to check down inside the casing.
|23. Hearing Inspection|
You can also use your sense of hearing to check for casing leaks. In areas where bedrock is close to the surface, listen for water running down into the well.
|24. Well Cap|
You should also inspect your well cap. A well cap is a tight-fitting, vermin-proof cap designed to prevent contaminants from flowing down inside of the well casing.
|25. Well Cap
Your well cap inspection should consist of two steps. First check to make sure that the cap is firmly installed. Second, make sure that the screened vent attached to the cap is intact. Any vent should face the ground, be tightly connected to the well cap, and properly screened to keep insects out.
|26. Casing Depth and
Well casing depth codes depend on the subsurface geologic materials and vary from state-to-state. Meeting well code minimums does not guarantee a safe water supply; you may want to exceed the minimum casing depth to help ensure a safe drinking water supply.
|27. Casing Depth|
Wells cased below the water level in the well afford greater protection from contamination. However, if the well is cased more than 20 feet into the water table you may end up with some water quality problems such as hard water or high levels of iron.
|28. Casing Height|
Typically, casing will extend one to two feet above the surrounding land. This is a water quality safety feature as it prevents surface water from running down the casing or on top of the cap and down into your drinking well water.
|29. Well Age|
Age is the third feature you should evaluate when assessing your drinking well water. This factor is important in predicting the likelihood of high nitrate concentrations in your well. Older wells are usually at the center of a farmstead and surrounded by potential contamination sources.
The older your well, the more likely it needs maintenance to repair possible water contamination problems. For instance, older well pumps are more likely to leak lubrication oils. In addition, older wells are likely to have thinner or metal casing which may have corroded through.
|31. Well Type|
There are three basic types of wells: dug wells, driven-point wells, and drilled wells. Dug wells shown in the left box are often shallow compared to driven-point and drilled wells. Drilled wells are commonly the deepest of the three wells.
|32. Dug Wells|
Dug wells usually have a large diameter hole which has probably been constructed by hand. These wells are usually very shallow, and consequently poorly protected from the threat of surface water contamination. Dug wells pose the highest risk of drinking water contamination.
|33. Driven-Point Wells|
The second type of well is called a driven-point or sand point well. These wells are constructed by driving assembled lengths of pipe into the ground. The pipe is normally two inches in diameter or less and the well is almost always less than 50 feet deep. These wells pose a moderate-to-high risk for contamination by pollutants found on small farms.
|34. Drilled Wells|
If the wells are not hand dug or driven-point they fall into the category of drilled wells. Drilled wells found on farms usually have a casing diameter of four to eight inches. If the wells are drilled into bedrock the casing diameter will be at least 6 inches. This type of well tends to have a lower risk for contamination than dug or driven-point wells.
|35. Well Depth|
Well depth is an important factor affecting the risk of drinking water contamination. In general, shallow wells draw groundwater nearest the land surface. This is the water most likely to be impacted by farmstead activities. Depth however, is not an all inclusive factor as both the depth of well casing below the water table and local geologic conditions affect water quality.
The third item to consider when trying to improve drinking well water quality is the current management and maintenance of your existing well. Good maintenance means: (1) testing your water every year, (2) keeping the well area clean and accessible, (3) keeping pollutants as far away from the well as possible, and (4) periodically having the well mechanics checked.
|37. Management and
Items to consider under management and maintenance of existing wells include: (1) better management of your existing well, (2) backflow prevention, (3) water testing, and (4) well maintenance.
|38. Better Management
Consider how well your existing well conforms to current state standards. You may want to move potential contamination activities further away from your well. You may want to upgrade your wells, get rid of well pits, install new caps, or extend casings.
|39. Wellhead BMPs|
Since changing the location of practices that may cause contamination may be expensive, maybe you should change your management practices of these facilities. So until you can meet minimum separation distances you can protect your drinking well water quality with management.
|40. Management BMPs|
Other management changes you can consider include: (1) moving traffic areas and chemical or gasoline storage areas away from the well, and (2) upgrading or better management of your septic system.
An important aspect of well management is backflow prevention. Backflow from pesticide mixing tanks allows chemicals to flow back into the well through the hose. You should use an anti-backflow device when filling pesticide sprayer tanks. Make sure to keep the hose out of the tank when filling your pesticide sprayer.
To protect your well, consider installing anti-backflow devices on all faucets with hose connections. Try and maintain air gaps between hoses or faucets and the water level. Anti-backflow devices will prevent having contaminated water in your washing machines, sinks, and/or swimming pools flow back through plumbing to contaminate your drinking well water.
Cross-connections are connections between two otherwise separate pipe systems. Water supplies with cross-connections between them put your drinking water at risk. Try to eliminate cross-connections.
This illustration shows both the right and wrong way to add water to a tank that may contain agrichemicals. The top figure represents the wrong way. Two things are wrong -- first the hose is submerged in the tank; second there is no air gap or backflow prevention device on the water line between the faucet and the well. The wrongs are corrected in the second illustration.
|45. Water Testing|
Whether to have or not have your water tested is a serious question that concerns your health and that of your family. Your water should be safe to drink and acceptable for all other household uses. Contaminated water can cause illness and perhaps even death. In addition, a variety of less serious problems such as bad taste, off-color, odor, and staining of clothes or fixtures are symptoms of water quality problems. People in cities and towns belong to municipal or community water systems where water testing is mandated by law. You, on the other hand, are ultimately responsible for your own water. There are three reasons for testing -- (1) your health, (2) your peace of mind, and (3) to evaluate the maintenance needs of your system.
|46. Annual Testing|
The best way to determine your present water quality is by annual testing. You can have your well tested for many parameters. Check with your local health district for advice about specific contaminant tests. At a minimum you should have your well water tested for bacteria and nitrate. In addition, it would be wise to test your well water for hardness, alkalinity, pH, conductivity, and chloride.
|47. Water Testing|
In addition to testing for the previously mentioned parameters, test for contaminants that are most likely to occur on your farmstead. Examples would include gasoline as fuel oil if you have storage tanks or specific pesticides if you store them in large quantities. You can obtain further advice on testing from your local health department or local Extension office. Water testing is done by both public and private laboratories. To find the lab closest to you consult with your local health department.
|48. Well Testing|
Remember that activities off your property can impact your groundwater! Chemical spills, changes in land use, and the presence of local landfills can all affect your drinking well water. Water testing should be conducted on an annual basis. Save your test results and note changes or trends over several years.
|49. Well Maintenance|
An important part of well management includes periodic maintenance. You should expect that your well should require mechanical attention every 10 to 20 years. A qualified well driller or pump installer should be called upon to perform this maintenance!
|50. Well Maintenance|
Other routine practices will help ensure safe drinking water from your well. Additional maintenance practices should include: (1) not using gas or chemicals near your well, (2) not mixing, rinsing, or discarding empty pesticide containers near your well, and (3) protecting wells from household wastewater treatment systems that may back up.
|51. New Wells|
The fourth item to consider when trying to improve drinking well water quality is to replace your existing well with a new well. It's true that new wells are expensive, but new wells are a good investment for the future. If you consider this option, locate the well away from contamination sources and work to maintain the quality of the well.
|52. New Wells|
When considering a new well, there are a few simple principles or BMPs to follow. These principles include: (1) following recommended minimum separation distances from potential pollution sources, (2) locating the well on ground higher than surrounding pollution sources, (3) avoiding areas prone to flooding,
|53. New Wells|
(4) if needed, building up the soil so that all surface water drains away from the well, (5) making sure that the groundwater flow generally follows surface drainage patterns,
|54. New Wells|
(6) making sure that the well is accessible for pump repair, cleaning, testing and inspection, and (7) being willing to hire a competent well driller and pump installer.
|55. Unused Wells|
If you have an unused well on your property, you need to shut it down. Unused wells can provide a direct path for surface water carrying pollutants to groundwater. Be willing to hire a licensed, registered well driller or pump installer to close your unused well.
In summary, it is apparent that many factors affect the quality of drinking water obtained from your well. The three ideas you should take home from this program are: (1) owning a well is a large responsibility because it can impact the health of your family, (2) you do not live on an island -- your neighbors can impact the quality of your well, and (3) management of your well and potential pollutants on your property can have a direct impact on you.
This slide script, WQ-25, was prepared by R. L. Mahler
and K. A. Loeffelman of the Soil Science Division, University of Idaho,
Moscow, Idaho 83844-2339.
This slide set and script was funded by a grant from the Pollution Prevention Program of the Environmental Protection Agency, Region 10.
Portions of this program have been adapted from Farm-A-Syst programs developed by the University of Minnesota, University of Wisconsin, and Kansas State University.
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All contents copyright © 1997-2003. College of Agricultural and Life Sciences, University of Idaho. All rights reserved. Revised: January 3, 2003