Is Your Well Protected From Your Pesticide Storage and Loading Facilities?
Proper management of your existing pesticide storage and loading facility will often protect your water supply without major expense. Even if the cost of modifying your facility is expensive, keep in mind that compared to the cost of a major accident or a lawsuit, storage and handling improvement costs can be a bargain.
The cheapest alternative you may have for storing your pesticides is, if possible, to cut back on the amounts and types of pesticides stored. Also consider how you can protect the pesticides you keep in storage.
Remodeling existing facilities that serve other uses may be less expensive than building a new facility, but remodeling can be complicated. When existing buildings must accommodate other activities, using them for pesticide storage could compromise the safety of people and the environment. Storing pesticides in a separate facility reduces the risk associated with fire or accidental spills. Never store pesticides inside a wellhouse or a facility containing an abandoned well. Building a new facility just for pesticide storage generally will be safer than trying to modify areas meant for other purposes.
Keep in mind the principles of safe pesticide storage mentioned below, and you will provide the maximum amount of safety possible for your family and your drinking water supply.
How Can We Help?
We have prepared this publication to help you focus on potential problems with your drinking water that may be caused by pesticides that are improperly stored, handled or disposed. Read this publication before you begin answering the questions. Gather any records you have about your pesticide storage and handling facility. Walk around and in the area where you store and load your pesticides. Also look at the area around your well.
Each of the following sections deals with different topics. Next to each topic is a question for you to answer. Your answers will help you to see where you have potential problems.
- If you answer a question either a or b, you have few problems with the storage, handling, or disposal of pesticides.
- If you answer a question either c or d, there may be potential problems with the way you store, handle, or dispose of pesticides.
- If you answer a question either c or d, you will want to consider making changes in the way you store, handle, or dispose of pesticides in order to protect your drinking water.
If you would like further help in assessing the condition of your pesticide storage and handling facilities, please visit your local N.C. Cooperative Extension center and talk with your Extension agent.
How Safe Is Your Drinking Water?
If you drink water from a well or spring, the water comes from the ground. Most groundwater in North Carolina is safe to drink. If pollution gets into groundwater, your well or spring water may not be safe. Many things we all do at our homes and farms can pollute the groundwater.
If groundwater becomes polluted, it is nearly impossible to clean up. Then, the only ways to get safe drinking water are to treat the existing water, drill a new well, or get water from another source. All of these options are expensive and inconvenient.
The North Carolina Farm*A*Syst program has a series of publications that can help you keep your drinking water safe. These publications will lead you through an evaluation of your farmstead to determine if your water is in danger of becoming or is already polluted with harmful substances from your farmstead area. If there is a problem or a potential problem, the Farm*A*Syst publications have information about how to solve the problems. The publications also list the North Carolina state agencies responsible for helping you solve your drinking water problem.
The goal of the North Carolina Farm*A*Syst program is to help you protect the groundwater that North Carolina residents depend on for drinking water.
Reducing the Risk of Groundwater Contamination by Improving Pesticide Storage
If stored safely in a secure location, pesticides pose little danger to groundwater. Keep pesticides dry and out of the way of activities that might knock over a jug or rip open a bag. Short-term storage (during seasonal use) poses a lower risk than year-round storage, but any storage, regardless of length of time, may pose a risk to groundwater.
Reducing pesticide waste makes financial as well as environmental sense, but it means more than just reducing spills. Buying only what you need makes long-term storage unnecessary. If you have pesticides that you do not plan to use: 1) return them to your pesticide dealer, 2) give them to someone who will use them properly (and who is certified if it is a restricted use pesticide), or 3) call the NC Department of Agriculture & Consumer Services, Structural Pest Control and Pesticides Division staff (919-733-3556) for instructions on the legal, proper disposal of pesticides.
Using older products first keeps your inventory current and effective. Before using chemicals that have been stored for a few years, check with your county extension agent about possible restrictions on their use.
Recordkeeping may seem like a task unrelated to groundwater contamination, but knowing what you’ve used in the past and what you have on hand allows you to use the older products first and make better purchasing decisions.
Keep records of past field application rates and their effectiveness. Along with field records, you can add information such as the manufacturer’s name and address, chemical types and handling precautions. This information can be important if you must respond quickly to an accident.
The risk of pesticide contamination of groundwater is influenced by properties of both the pesticide and the soil on which it is spilled or applied. Some pesticides bind tightly to soil particles; other pesticides are very mobile in soil and can move (leach) easily through the soil into the groundwater.
Some pesticides come in several forms, such as dry granules or liquid. The dry form of pesticides, although bulkier to store and load, is easier to clean up if there is a spill. These can be swept up and used according to the label. Liquid forms of pesticide, however, will need to be soaked up using an absorbent material which has to be handled in one of two ways (see "How do you handle an accidental spill while you are loading your pesticides?" below).
The closer the pesticide storage area is to your well, the greater the risk of contamination. Pesticide storage areas should be downslope and at least 50 feet from your well to provide reasonable assurance that well water will not be contaminated (see Figure 1). The distance between the two should be greater if the site has sandy soils or fractured bedrock near the land surface.
Safe storage can minimize the risk of spills around your pesticide storage area. If a spill does occur, an impermeable (waterproof) floor, such as coated or sealed concrete, should virtually eliminate any seepage of pesticides into the ground. An eight-inch berm around the floor will contain spills and allow for easier cleanup.
Pesticides should always be stored in sound, properly labeled, original containers. Each container should be labelled with the:
- Common chemical name
- Percentage of each active ingredient
- US Environmental Protection Agency (EPA) registration number
- Signal word
- Classification of uses (restricted use or general use).
Sound containers are your first defense against a spill or leak. If a container is accidentally ripped open or knocked off a shelf, the spill should be confined to the immediate area and cleaned up promptly.
Steel shelves are easier to clean than wood if a spill occurs. Shelves for smaller containers should have a lip to keep the containers from sliding off.
Store dry products above liquids to prevent wetting from spills. Provide pallets to keep large drums or bags off the floor.
Keep pesticides separate to prevent cross-contamination. Herbicides, insecticides, and fungicides should be kept on separate shelves or areas.
Pesticide storage areas must be kept free from combustible materials (such as petroleum products) or other operations that present a fire hazard (such as welding).
If you plan to store large bulk tanks, provide a containment area large enough to confine 125 percent of the contents of the largest bulk container, plus the displaced volume of any other storage tanks in the area. The Pesticide Section, Structural Pest Control and Pesticides Division of NCDA&CS can provide information on the use of bulk containers and their location. For more information, contact them at 919-733-3556. A pesticide storage area cannot be closer than 50 feet to a private well and 100 feet to a public well.
Pesticide storage cabinets or buildings should be locked any time the owner or his employees are not present. A locked storage cabinet or building provides security, preventing unauthorized use of pesticides and reducing the chance of accidental spills or theft (Figure 2). It is a good idea to provide signs or labels identifying the cabinet or building as a pesticide storage area. For commercial pesticide facilities or storage areas used by licensed pesticide applicators, a warning sign shall be posted beside all entrances to the pesticide storage area stating: “PESTICIDE STORAGE,” “AUTHORIZED PERSONNEL ONLY,” and “IN CASE OF EMERGENCY CALL (the local emergency number).”
Fires in a storage area present a special hazard to people and the environment. You can reduce damages by anticipating emergencies. Label windows and doors to alert firefighters to the presence of pesticides. Also, consider where the surface runoff water will go and where it might collect, if water were introduced due to fire. For example, a berm around a floor can help confine contaminated water. In making the storage area secure, also, make it accessible to allow getting pesticides out in a hurry. A pre-fire plan is also a good idea and your local fire department can assist in preparing one. Commercial pesticide facilities or licensed pesticide applicators are required to have this type of plan if they store restricted used pesticides. Keeping an updated list of all pesticides is another safety precaution so that in the case of an emergency, such as a fire, emergency workers are aware of any dangers they might encounter.
Reducing the Risk of Groundwater Contamination by Improving Pesticide Mixing, Loading, and Disposal Practices
It doesn’t take much to contaminate groundwater. Keep in mind that 1 part per billion (ppb) in groundwater can come from 1% of an application of one pound of active ingredient per acre. The legal limits for some of the major herbicides in drinking water are equal to or slightly above 1 ppb.
Just as it is important to keep your storage area away from your well, it is also important to keep your mixing and loading site as far away from your well as possible. Spilled pesticides can move through the soil into the groundwater and pollute your drinking water supply. All spills must be cleaned up completely. The farther your mixing and loading site is placed from your well, the greater the protection to your drinking water supply.
Groundwater contamination can result even from small spills in the mixing and loading area. Small quantities spilled regularly in the same place can go unnoticed, but the chemicals can build up in the soil and eventually reach groundwater.
Mixing and loading on an impermeable (waterproof) surface, such as coated or sealed concrete, will catch most of the spilled pesticides. Avoid mixing and loading on gravel driveways because spills move quickly through the gravel and into the soil. A clay surface is better than sand or gravel, because clay slows pesticide movement into the soil.
Your mixing and loading pad should be large enough to contain leaks from bulk tanks, wash water from cleaning equipment, and spills occurring during transfer of chemicals to the sprayer or spreader. The pad should have a slight slope to a drain where a sump pump can pump the spill and rinse water to a tank.
The optimum size of the pad depends also on the equipment you use. The pad should provide space around the parked equipment for washing and rinsing. Having several rinsate (rinse water) storage tanks allows you to keep rinsate from different chemicals separate. That way, the rinsate can be used as mixing water on subsequent loads. Be sure that field runoff does not run over the pad.
The best design of a new storage facility includes a mixing/loading pad as part of the whole plan (see Figure 3). This reduces the costs of both and keeps all of the spill risks contained in one place. See the figure below for an example. If you are considering constructing a mixing and loading pad, contact your county Cooperative Extension center for more detailed information. Information on other factors to consider in the design of a storage facility — such as ventilation, temperature control and worker safety — is also available.
Avoid mixing and loading pesticides near your well. One way to do this is to use a nurse tank to transport water to a mixing and loading site in the field (see Figure 4). Ideally, the field mixing site should be moved around within the field of application.
You need to install a backflow prevention device on the well or hydrants to prevent reverse flow of liquids into the water supply (see Figure 5). Never put the hose in the sprayer tank. Pesticides can be sucked back into your well. Be sure to provide an air gap of six inches between the hose and the top of the fill line in the sprayer tank.
You should always stay with your sprayer during filling. For restricted use pesticides, a trained and certified applicator must supervise operations.
A closed handling system for liquids, which transfers the pesticide directly from the original container to a mixing valve where water is mixed with the pesticide immediately prior to spraying, is the safest way to load and mix pesticides. Humans and the environment are not exposed to the concentrated pesticide with this system, and when spraying is completed, your remaining pesticide concentrate is still in the container for later use. Another system (see Figure 6) uses the water pumped from the nurse tank to empty the pesticide container while filling the spray tank.
All empty containers must be thoroughly rinsed using a pressure nozzle, which is more effective, or by triple rinsing (see Figure 7). To triple rinse your container, fill your container one-half full, rinse and pour the rinsate into your spray tank. Repeat this procedure two more times. Rinsing your pesticide containers during the spray operation prevents the pesticide from drying on the container and allows you to immediately dispose of the rinsate into the spray tank.
Improper disposal of pesticide containers can lead to groundwater contamination because the chemical residue can leak into the ground. Some basic guidelines can help avoid similar problems:
- As often as possible, use returnable containers and minibulks and take them back to the dealer.
- Puncture rinsed containers and store them in a locked storage area until you can take them to a permitted landfill or recycling center.
- Shake out bags, bind or wrap them to minimize dust, and take them to a permitted landfill.
- Do not bury or burn pesticide containers or bags on the farm.
For more information about disposing of hazardous waste either contact the:
- NCDA&CS, Structural Pest Control and Pesticides Division, Pesticides Section, 919-733-3556, or
- NCDENR, Division of Waste Management, Hazardous Waste Management Section, 919-707-8200.
How Do You Handle an Accidental Spill While You Are Loading Your Pesticides?
If you spill pesticide while you are loading, you need to follow different procedures depending on whether the pesticide is in dry or liquid form. For dry spills, promptly sweep up and use the pesticide as it was intended. Dry spills are usually very easy to clean up. For liquid spills, the first thing to do is contain the spill so it cannot move off-site. Then, recover as much of the spill as possible using soils, sawdust, or other absorbent material, and place all materials in a sealable container. The spilled pesticide and any materials used to absorb it can be applied to sites for which it is labeled. You will have to estimate how much was spilled and calculate how much land to apply the spilled material to, based on the label rate. Contact the NCDA&CS Structural Pest Control and Pesticides Division staff (919-733-3556) for instructions on the legal, proper disposal of pesticides.
Spills that have the potential to cause problems for people or the environment should be reported immediately by calling 911 or local emergency responders. The NCDA&CS Structural Pest Control and Pesticides Division staff (919-733-3556) can provide technical assistance. Pesticides classified as hazardous chemicals and extremely hazardous chemicals have reporting requirements depending upon the amount of pesticide active ingredient spilled. Some chemical companies have toll free numbers on the label for use in case of accidents.
Have an emergency response plan for your loading and mixing site. Know where runoff water will go, how to handle your particular pesticides, and whom to call for help.
Additional Information and Acknowledgments
Related publications available:
The concept for these materials was adapted from materials produced by the National Farm*A*Syst Program, University of Wisconsin, Madison, WI.
North Carolina’s Farm*A*Syst Program is coordinated by Deanna L. Osmond, North Carolina State University. Technical editing was provided by Judith A. Gale, and copy editing by Cathy Akroyd. Gordon S. Miner and Michael T. Vepraskas were the technical reviewers at North Carolina State University. Technical review was also provided by Henry F. Wade, Pesticides Section, Structural Pest Control and Pesticides Division, North Carolina Department of Agriculture & Consumer Services.
This project has been funded with Section 319 grant monies from the US Environmental Protection Agency through the NC Department of Environment and Natural Resources, Division of Water Infrastructure.
This publication is a revision of an earlier version. The author would like to thank D. Osmond & J. Gale for their earlier contributions.
Publication date: March 2, 2014
Revised: Sept. 18, 2023
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