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A vertical air break separation (gap) between the free flowing discharge end of a water supply line and the fill opening of a water storage tank. An approved separation should be at least 1" or two times the diameter of the supply line measured vertically above the overflow rim of the tank. The supply line is usually fitted with a float controlled shutoff.
A check valve or other mechanical device to prevent unwanted reverse flow of liquids back down a water supply pipe into a well.
Check valves should be installed in all rinse water or mixture handling lines. Valves for horizontal piping must be spring loaded. Spring-loaded valves can be used in any position. Valves in vertical piping can be gravity activated valves.
Check valves can fail when dirt or rust particles become wedged between the valve and the seat. Check for good operating and proper backflow sealing prior to operating the complete anti-backflow system. Provide shutoff valves to isolate system components for maintenance or emergencies.
A system for transferring pesticides or fertilizers directly from storage containers to applicator equipment (through a hose, for example), so that humans and the environment are never inadvertently exposed to chemicals. Ideally, closed system transfer is accomplished by means of a vacuum but other pump systems are also used.
Pesticides and fertilizers are stored in a variety of containers, including paper bags, cardboard boxes, glass jugs, refillable plastic containers and metal tanks.
Any deterioration in the original packaging - such as rips and tears in paper containers and rust on steel containers - is a potential source of chemical leaks. If containers are showing signs of wear and tear or weathering, replace them with well labeled new containers.
Cracks in the floor of the storage area and mixing pad rarely affect the structural integrity or durability of the facility but they may provide an escape route for spilled or leaked chemicals. Small quantities of chemicals spilled on a regular basis could travel through cracks in the floor into the soil and thus reach the groundwater.
Note: Active cracks that are increasing in size deserve more attention. Identify the cause of such cracking before attempting repairs.
Curbs on the mixing and loading pad and on the storage floor help contain spills and leaks. This type of secondary containment therefore reduces the risk of environmental damage and provides a means of holding escaped product until it can be properly cleaned up. Curbs should be high enough to contain the contents of the largest container inside the storage area.
A barrier constructed to contain, divert or direct a liquid flow. In this case, usually an earthen dike built for the secondary containment of fertilizer and pesticide storage facilities.
There is no ideal method of pesticide container disposal, therefore the best strategy is to minimize the number of containers requiring disposal.
Dissolution is the process whereby mineral or rock material is dissolved due to chemical weathering.
Flooring in pesticide storage areas should be watertight, chemically impermeable and skid resistant. Concrete floors with an impervious sealant or an equivalent material that provides strength and impermeability should be used. Curbs should be added for spill collection.
Wood, gravel and soil floors/pads will allow spilled or leaked chemicals to pass through into the soil, thus increasing the risk of groundwater contamination. Wood surfaces may temporarily collect spills so that most of a spill can be cleaned up. However, some chemical will still be transferred.
Pesticide form can effect both the risk of contaminating the environment and worker safety. Generally, dry granular forms are safer than liquids.
Liquid spills are harder to contain and clean-up. Liquids are more often stored in glass containers than dry formulations. Glass containers can break if dropped or exposed to freezing temperatures.
Some liquids are quite flammable and thus must be stored more carefully. Vapors from liquids can also create a safety hazard to workers.
Groundwater is the water under the surface of the earth that is found within the pore spaces and cracks between the particles of soil, sand, gravel and bedrock.
How to hand rinse rigid pesticide containers:
You can use either a homemade rinse nozzle or a commercial nozzle.
Hydrogeology is the study of groundwater.
Impermeable floor pads are ones that do not allow fluids to seep through them. Concrete, steel, and asphalt floors are normally impermeable while wood and soil floors are not.
Pesticide container label condition does not directly affect water contamination risk but missing or illegible labels could result in improper storage and use of a chemical. Also, should a spill or leak occur, it may be harder to assess the potential damage of the accident and deal properly with the spilled material if labels are in poor condition or missing.
Leaching is the process whereby water travels down through a soil, carrying nutrients and other chemical compounds with it.
The leachability, or ease of leaching, of a pesticide depends upon how water-soluble it is and how strongly it adsorbs to the soil. The higher the leachability of a compound, the greater the risk of it being transported down to the groundwater system.
Sometimes an impermeable liner is installed below a storage tank to help contain leaks or spills.
A pesticide mixing and loading facility serves many purposes and thus must have certain characteristics:
Non-pont source contamination refers to pollution from numerous widespread locations that are hard to identify, such as leaching of pesticides from fields on which they were applied.
Pads for mixing and loading pesticides should be constructed from an impermeable uncracked material. It should include curbs to contain spills and be sloped towards a sump to facilitate spill collection.
A pesticide is the general name for any chemical, substance, or mixture intended to prevent, destroy, repel, or mitigate a pest (weeds, insects, rodents, fungi, etc.). Includes:
A well designed pesticide storage facility protects human welfare, wildlife, the surface environment, and groundwater system from accidental and working exposure to pesticides.
Point source contamination of groundwater refers to pollution from one place that is easy to identify, as this type of contamination is usually characterized by concentrated pesticide plumes that are relatively localized.
This category includes accidental spills and leaks of pesticides on the farm where they are stored and handled in bulk quantities. It also includes backsiphoning of pesticides into irrigation water wells not equipped with proper safety devices. Because of the character of point source contamination, those who are responsible for an incident can often be identified and required to pay for the cleanup. Groundwater cleanup can be extremely expensive.
Porosity is the ratio of the volume of pore (non-rock or non-sediment) spaces in a rock or sediment to the total volume (rock or sediment + pore spaces).
Primary porosity is the porosity that develops in sediment during the final stages of sedimentation or is present within the particles during deposition.
Secondary porosity is the porosity that develops in the rock or sediment after its deposition, by means of such processes as dissolution or fracturing.
Pressure rinsing is much faster than triple-rinsing. It is also a more effective method for the removal of pesticide residue. This method, however, can only be used on plastic and non-pressurized metal containers. In pressure-rinsing, a special nozzle, attached to the end of a water hose, is used to force any pesticide residue out of the empty container.
To pressure-rinse an empty pesticide container:
Rinsate is water, and sometimes solids, contaminated with pesticides or fertilizer of relatively low concentration. Rinsate becomes waste and a potential contaminant if it cannot be used according to the product label.
Rinsate is generated by hand rinsing and by pressure rinsing pesticide containers.
How to take a water sample for testing:
Secondary containment is provided by structures built around storage facilities and mixing/loading areas to contain products that have escaped due to leaks, spills, fire, impacts, vandalism, etc.. It is a safety back-up system designed to prevent escaped compounds from contaminating the environment until the site can be cleaned. Typically consist of a curb, wall or dike constructed around the storage tanks.
Examples for inside storage structures:
Examples for outside storage areas:
Storage security is required to prevent accidental poisoning of children, wildlife and livestock. It also minimizes unauthorized access to chemicals, thus reducing the potential for spills, vandalism and theft. Locate the storage in an isolated area, far from other activities.
For an open facility:
For an enclosed structure:
The type of soil in a region affects soil compaction, permeability, drainage, plant growth, and fluid flow rates. These properties in turn effect the rate of contaminant entry and transport through the soil profile into the water system.
In general, soil textures and drainage classes are as follows:
A sump is a pit or reservoir serving as a receptacle for liquids. A sump is not considered storage but rather is designed for immediate liquid recovery and transfer.
The risk of drinking water supply contamination due to pesticide storage depends upon the amount of pesticide stored and it's format. Risk is greater for liquids than dry products and increases with the amount of product stored.
Water absorbs dissolved minerals, organic compounds, and micro-organisms as it moves through the air and soil into surface and ground water supplies. Unacceptable materials can get into the water by naturally means and through man's actions.
Some contaminants will change the appearance, taste or smell of water. However, many of the most toxic contaminants do not provide sensory clues. Water testing may be the only way of determining whether water is contaminanted and the degree of contamination.
Public water systems ensure the safety of the water they deliver. Private well owners are responsible for ensuring the quality of their drinking water. Testing for every possible contaminant is expensive and unnecessary. Instead, you should regularly perform tests for "contamination indicators", and select hazards.
Pesticides are transferred from storage to the mixing vessels in a number of ways. These methods are divided into 3 categories: hand transfer, closed transfer system, and combination systems.
The risk of accidents and spills increases as the amount of hand transfer operations increases.
Triple rinsing is the most common method of rinsing pesticide containers. However, it is a slower and less effective method of removing residue from empty containers than pressure-rinsing. Triple rinsing can be used on plastic, glass, and non-pressurized metal containers.
To triple-rinse an empty pesticide container:
The vadose zone is the region between the ground surface and the zone of saturation. Within the vadose zone, the pore spaces between the soil and/or rock particles are partly filled with water and partly filled with air.
Interior pesticide storage walls and floor surfaces should be impervious to pesticides and easily cleaned and decontaminated. Painted steel, aluminum, fiberglass or high density plastic reinforced plywood panels are good choices for wall liners.
The water table is the level at which the water stays. The very top of the zone of saturation. Water can also be found a few centimeters above this level water due to capillary action.
In the presence of a pumping well, the water table drops near the well. This situation is called drawdown. Under some conditions, a perched water table may exist. This occurs when the water percolation is interrupted by another confining layer above the "main" one.
Water quality standards are set by the U.S. Environmental Protection Agency. These standards represent contaminant levels that are allowed in public water supplies and are set to protect the health of the public. State governments can impose additional, stricter limits.
Limits are generally stated as concentrations, in either:
There are many possible contaminants of water. Tests vary in price from a few dollars to several hundred. Therefore, you should only test for likely contaminants - based on sensory clues and location hazards - and indicators of contamination.
The frequency of testing varies with each contaminant. Bacteria and nitrate test should be performed yearly. These materials indicate that a larger problem may exist. Test should also be done any time a change in water color, odor or taste are noticed, when plumbing has been changed, if flooding has occurred near the well, or there has been reoccurring human or livestock disease that could be waterborne.
Clues & Local Activities to Consider:
The zone of saturation is the region beneath the vadose zone in which all of the pore spaces between the soil and/or rock particles are filled with water. The upper surface of this zone is called the water table.
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