Assessing the Risk of Groundwater Contamination From Pesticide Storage and Handling
Farm•A•Syst: Farmstead Assessment System Worksheet #2
Included when you order this worksheet: MU publication EQ676, Reducing the Risk of Groundwater Contamination by Improving Pesticide Storage and Handling, the fact sheet that corresponds with this worksheet.
Pesticide storage and handling: Assessing drinking-water contamination risk
|Low risk, rank 4||Low to moderate risk, rank 3||Moderate to high risk, rank 2||High risk, rank 1||Your rank|
|Amount stored||No pesticides stored at any time.||Less than 1 gallon, or more than 10 pounds of each pesticide.||More than 1 gallon, or more than 10 pounds of each pesticide.||More than 55 gallons, or more than 550 pounds of each pesticide.|
|Location of pesticide storage area in relation to well||300 feet or more downslope from well.||50 to 300 feet downslope from well.||150 to 150 feet downslope from well.1||Within 50 feet or up-slope from well.1|
|Leachability (See Pesticide chart.)|
Liquid or dry formulation
|No pesticides stored.|
No liquids. All dry.
|Pesticides classified as having low leaching potential.|
Some liquids. Mostly dry.
|Pesticides classified as having medium leaching potential.|
Mostly liquids. Some dry.
|Pesticides classified as having high leaching potential.|
|Spill or leak control in storage area||Impermeable surface (such as concrete), does not allow spills to soak into soil. Curb installed on floor to contain leaks and spills.||Impermeable surface with curb installed has some cracks, allowing spills to get to soils. OR impermeable surface without cracks, has no curb installed.||Permeable surface (wooden floor), has some cracks. Impermeable surface, has no curb. Spills could contaminate wood or soil.||Permeable surface (gravel or dirt floor). Spills could contaminate floor.|
|Containers||Original containers clearly labled. No holes, tears or weak seams.||Original containers old. Labels partially missing or hard to read.||Containers old but patched. Metal containers show signs of rusting.||Containers have holes or tears that allow chemicals to leak. No labels.|
|Security||Fenced or locked area separate from all other activities.||Fenced area separate from most other activities.||Open to activities that could damage containers or spill chemicals.||Open access to theft, vandalism and children.|
|Mixing and loading practices|
|Location of well in relation to mixing/loading area with no curbed and impermeable containment area||150 feet or more from well.||100 to 150 feet downslope from well1||50 to 100 feet downslope from well,1or 100 to 500 feet upslope.||Within 50 feet downslope, or within 100 feet upslope from well.1|
|Mixing and loading pad (Spill containment)||Concrete pad with curb keeps spills contained. Sump allows collection and transfer to storage.||Concrete pad with curb keeps spills contained. No sump.||Concrete pad with some cracks keeps some spills contained. No curb or sump.||No mixing/loading pad. Permeable soil (sand). Spills soak into ground.|
|Backflow prevention on water supply||Anti-backflow device installed or 6-inch air gap maintained above sprayer tank.||Anti-backflow device installed. Hose in tank above waterline.||No anti-backflow device. Hose in tank above waterline.||No anti-backflow device. Hose in tank below water line.2|
|Water source||Separate water tank||Hydrant away from well.||Hydrant near well.||Obtained directly from well.|
|Filling supervision||Constant supervision||Frequent.||Seldom.||Never.|
|Handling system||Closed system for all liquid and dry product transfers.||Closed system for most liquids. Some liquid and dry product hand poured. Sprayer fill port easy to reach.||All liquids and dry product hand poured. Sprayer fill port easy to reach.||All liquids and dry product hand poured. Sprayer fill port hard to reach.|
|Sprayer cleaning and rinsate (rinse water) disposal||Sprayer washed out in field.||Sprayer washed out on pad at farmstead. Rinsate used in next load and applied to labeled crop.||Sprayer washed out at farmstead. Rinsate sprayed less than 100 feet from well.||Sprayer washed out at farmstead. Rinsate dumped at farmstead or in field.2|
|Disposal location||Triple-rinsed containers returned to dealers or taken to licensed landfill or municipal incinerator. Bags returned to supplier, or hazardous waste collection service used.||Unrinsed containers and empty bags taken to licensed landfill, municipal incinerator or dump.||Disposal of unrinsed containers or empty bags on farm. Disposal of triple-rinsed containers on farm.||Disposal of partially filled plastic or paper containers on farm. Bags buried in field or burned on farm.|
1Illegal for new well installation. Existing wells must meet separation requirements in effect at time of construction.
2Besides representing a higher-risk choice, this practice also violates Missouri law.
Why should I be concerned?
Pesticides are showing up where they're not wanted — in our drinking water. If pesticides are not handled carefully around the farmstead, they can seep through the ground after a leak or spill, or they can enter a well directly during mixing and loading.
Pesticides play an important role in agriculture. They have increased farm production, and they have enabled farmers to manage more acres with less labor.
Pesticides work by interfering with the life processes of plants and insects. Pesticides also may be toxic to people. If pesticides enter a water supply in large quantities — as can happen with spills or backsiphonage accidents — acute exposure (toxic effects apparent after only a short period of exposure) can range from moderate to severe, depending on the toxicity of the pesticide and the amount of exposure. Contaminated groundwater used for drinking-water supplies may result in chronic exposure (prolonged or repeated exposure to low doses of toxic substances), which may be hazardous to people and livestock.
When found in water supplies, pesticides normally are not present in high-enough concentrations to cause acute health effects, which can include chemical burns, nausea and convulsions. Instead, they typically occur in trace levels, and the concern is primarily for their potential for causing chronic health problems from prolonged exposure.
Your drinking water is least likely to be contaminated if you follow appropriate management procedures and properly dispose of wastes in a location that is off the farm site. However, proper offsite disposal practices are essential to avoid risking contamination that could affect the water supplies and health of others.
How will this worksheet help me protect my drinking water?
It will take you step by step through your pesticide handling, storage and disposal practices.
- It will rank your activities according to how they might affect the groundwater that provides your drinking-water supplies.
- It will provide you with easy-to-understand rankings that will help you analyze the "risk level" of your pesticide handling, storage and disposal practices.
- It will help you determine which of your practices are reasonably safe and effective and which practices might require modification to better protect your drinking water.
How do I complete the worksheet?
Follow the directions at the top of the next chart. It should take you about 15 to 30 minutes to complete this worksheet and figure out your ranking.
Pesticide Leachability Chart
|The pesticides listed on this chart are identified by brand name, common name and rating for movement by leaching (low, medium or high). Identify the pesticides stored on your farmstead from the listing below. Note the "leachability factor" for each pesticide you store. Then give yourself an overall "leachability ranking" (low, medium or high), based on which ranking best represents the pesticides you store. Then use this ranking to complete the "Leachability" section on the assessment worksheet.|
|Brand name||Common name||Rating for movement by leaching|
|Betamix||phenmedipham and desmedipham||Low|
|Bicep||metolachlor and atrazine||Med|
|Bronate||bromoxynil and MCPA ester||Low|
|Bronco||glyphosate and alachlor||Low|
|Buckle||triallate and trifluralin||Low|
|Buctril-Atrazine||bromoxynil and atrazine||Low|
|Butyrac 200||2,4-DB amine||Med1|
|Cannon||alachlor and trifluralin||Med|
|Commence||trifluralin and clomazone||Low|
|Crossbow||triclopyr and 2,4-D ester||Med|
|Curtail||clopyralid and 2,4-D amine||High|
|CurtailM||clopyralid and MCPA ester||High|
|ExtrazineII||atrazine and cyanazine||High|
|Galaxie||bentazon and aciflourfen||High|
|Harmony||DPX-M6316 and Extra DPX-L5300|
|Laddock||atrazine and bentazon||High|
|Lariat||alachlor and atrazine||Med|
|Lasso Micro Tech||alachlor|
|Lasso- Atrazine||alachlor and atrazine||Med|
|LoroxPlus||linuron and chlorimuron||Med|
|Marksman||dicamba and atrazine||High|
|MCPA Amine||MCPA amine|
|MCPA Ester||MCPA ester||Low|
|Preview||metribuzin and chlorimuron||High|
|Prozine||pendimethalin and atrazine||Low|
|Pursuit Plus||imazethapyr and pendimethalin||-|
|Ramrod- Atrazine||propachlor and atrazine||Low|
|Rescue||naptalam and 2,4-DB||Med1|
|Salute||metribuzin and trifluralin||High|
|Stampede CM||propanil and MCPA ester||Low|
|Storm||bentazon and acifluorfen||High|
|Sutazine+||butylate and atrazine||Med|
|2,4-D amine||2,4-D amine||Med|
|2,4-D ester||2,4-D ester||Low1|
|Turbo||metolachlor and metribuzin||Med|
|Weedone- 2,4-DP||dichlorprop ester||-|
|Endocide Plus||endosulfon and parathion||High|
|Malathion/ methoxychlor||malathion and methoxychlor||Low|
|Agsco MNF||maneb and|
|Blitex||maneb and triphenyltin||Low2|
|Maneb and||maneb and||Low2|
1The rating is an estimate, but reasonably accurate compared to estimated ratings footnoted with a 2.
2The rating is a guess, and subject to a higher degree of error than estimates footnoted with a single asterisk.
Adapted from Becker, R.L., et al. 1990, Pesticides: Surface Runoff, Leaching, and Exposure Concerns. Minnesota Extension Service. Data were derived from U.S. Department of Agriculture SCS/ARS Pesticides Properties Data Base, Version 1.9, August 1989, developed by R.D. Wauchope et al., and ratings derived by D.W. Goss.
Chart modified annually. Contact your Natural Resources Conservation Service (NRCS) or local MU Extension center for the most recent version.
What do I do with these rankings?
Begin by determining your overall well management risk ranking using Equation 1.
Total the rankings for the categories you completed, and divide by the number of categories you ranked:
|(total of rankings)||(number of categories ranked)||(risk ranking1)|
1Carry your answer out to one decimal place.
|If your risk ranking is||Your risk is|
|3.6 to 4||low|
|2.6 to 3.5||low to moderate|
|1.6 to 2.5||moderate to high|
|1 to 1.5||high|
This ranking gives you an idea of how your well management practices as a whole might be affecting your drinking water. This ranking should serve only as a general guide, not a precise diagnosis. Because it represents an average of many individual rankings, it can mask any individual rankings (such as 1s or 2s) that should be of concern. (Step 2.)
Enter your well management risk ranking above in the first table in Worksheet #9 (MU publication WQ659). Later you will compare this risk ranking with other farmstead-management rankings. Worksheet #8 (MU publication WQ658)
Look over your rankings for individual activities:
- Low-risk practices (4s)
ideal; should be your goal despite cost and effort
- Low- to moderate-risk practices (3s)
provide reasonable groundwater protection
- Moderate- to high-risk practices (2s)
inadequate protection in many circumstance
- High-risk practices (1s)
inadequate; pose a high risk of polluting groundwater
Regardless of your overall risk ranking, any individual rankings of "1" require immediate attention. Some concerns you can take care of right away; others could be major — or costly — projects, requiring planning and prioritizing before you take action.
Find any activities that you identified as 1s and list them under "High-Risk Activities" in Worksheet #9 (MU publication WQ659).
- Abandoned water well
A well that is permanently discontinued or that is in such disrepair that its continued use for obtaining groundwater is impractical or may be a health hazard.
- Air gap
An air space (open space) between the hose or faucet and water level, representing one way to prevent backflow of liquids into a well or water supply.
- Anti-backflow (anti-backsiphoning) device
A check valve or other mechanical device to prevent unwanted reverse flow of liquids back down a water-supply pipe into a well.
A water-bearing formation (soil or rock horizon) that transmits water in sufficient quantities to supply a water well.
- Bored wells
Wells constructed using augers, scoops, drag lines or similar equipment. These holes are usually of large diameter and are constructed in alluvial or glacial material.
An impervious durable pipe placed in a well to prevent the walls from caving and to seal off surface drainage or undesirable water, gas or other fluids to prevent them from entering the well.
A link or channel between pipes, wells, fixtures or tanks carrying contaminated water and those carrying potable (safe for drinking) water. Contaminated water, if at higher pressure, enters the potable water system.
- Drilled wells
Wells not dug or driven, including those constructed by a combination of jetting or driving. These wells are normally 4 to 8 inches in diameter.
- Driven-point (sand point) wells
Wells constructed by driving assembled lengths of pipe into the ground with percussion equipment or by hand. These wells usually are smaller in diameter (2 inches or less), less than 50 feet deep and can be installed in areas of relatively loose soils, such as sand.
- Dug wells
A well in which the side walls may be supported by material other than standard weight steel casing. Water enters a dug well through the sides and bottom.
The water in the zone of saturation in which all of the pore spaces of the subsurface material are filled with water. The water that supplies springs and wells is groundwater.
Slurry of cement or bentonite clay used to seal the annular space between the outside of the well casing and the bore hole. Also used in sealing abandoned wells.
- Milligrams per liter (mg per liter)
The weight of a substance measured in milligrams contained in 1 liter. It is equivalent to 1 part per million in water measure.
- Parts per million (ppm)
A measurement of concentration of one unit of material dispersed in 1 million units of another.
- Pressure grout
Refers to the process of applying grout material under pressure to the annular space of a well to seal it and thus prevent vertical movement of fluids through the annular space. Grout must be introduced from the bottom of the annular space.
- Water table
The upper level of groundwater in a zone of saturation. Fluctuates with climatic conditions on land surface and with aquifer discharge and recharge rates.
- Well cap (seal)
A method or device used to protect a well casing or water system from the entrance of any external pollutant at the point of entrance into the casing.