9.1 Planning the Application: Safe Mixing, Loading, Measuring & Rinsate Management
Key Takeaways
- Choose a mixing and loading site that is level, away from wells and surface water, and where a spill can be contained and recovered.
- Never leave a filling tank unattended, and always maintain an air gap or use an anti-backflow device so tank contents cannot siphon into a water source.
- Triple rinsing means three separate rinses with the rinsate poured into the spray tank each time; pressure rinsing achieves the same result in a single 30-second operation.
- Rinsate is a pesticide and is best used by applying it to a site listed on the label at labeled rates, never poured out or sent to a storm drain.
- Mix only what will be applied; leftover spray solution is the single most common source of disposal problems.
9.1 Planning the Application: Safe Mixing, Loading, Measuring & Rinsate Management
Chapter 10 of the core manual is titled Planning the Pesticide Application, and it exists because most exposure, most contamination, and most waste are created before a single nozzle opens.
1. Choosing the Mixing and Loading Site
A good mix-and-load site is:
- Level, so containers and equipment do not tip and so a spill flows to a predictable place.
- Away from wells, springs, ditches, canals, and surface water. A permanent site should be as far from any water source as the property allows, and a sealed containment pad is the best available protection.
- Away from where people, children, livestock, and pets congregate.
- Free of storm drains and floor drains. Anything reaching a storm drain reaches surface water untreated.
- Varied, if the site is temporary. Loading in a different spot each time avoids building a concentrated residue in one location, which is what makes an unimproved permanent loading site a long-term point source.
Utah's rules reinforce all of this. R68-7-19(6) prohibits handling, storing, loading, applying, or disposing of any pesticide, container, apparatus, or rinsate in a manner that pollutes water supplies or waterways; R68-7-19(7) prohibits polluting streams, lakes, or other water supplies during loading, mixing, and application and requires appropriately functioning devices and procedures to prevent back siphoning.
2. Personal Protective Equipment for Mixing and Loading
Read the label's PPE section carefully: many labels require more protection for mixers and loaders than for applicators — commonly chemical-resistant gloves, apron, footwear, and eye protection at minimum, because concentrate is being handled. Where the label permits reduced PPE with a closed system, that reduction applies only while the closed system is actually in use.
3. Measuring and Transferring
- Read the label again before opening the container. Confirm rate, carrier volume, mixing order, and any required adjuvant.
- Calculate first, then measure. Know the number of gallons the tank will hold and the amount of product for that volume before you open anything.
- Use dedicated measuring equipment, marked and used for pesticides only, never for anything else, and rinsed into the tank after use.
- Open containers carefully, keeping your face away from the opening, and cutting rather than tearing paper packaging so dust is not released.
- Stand upwind and keep the container below eye level while pouring.
- Transfer at a controlled rate. Most splash exposures come from pouring too fast from a container that is too heavy.
- Follow the label's mixing order. Adding a wettable powder to an empty tank or adding an emulsifiable concentrate before the tank is partly filled with water are classic causes of an unusable mix.
4. Filling the Tank
- Never leave a filling tank unattended. An overflow while the operator is elsewhere is the most common serious contamination event at a farm loading site.
- Maintain an air gap between the fill hose outlet and the tank's top opening, or use an approved anti-backflow device. A hose left submerged in the spray solution can siphon tank contents into the water supply when pressure drops.
- Do not fill directly from a stream, canal, pond, or wellhead without an air gap or backflow prevention — this is exactly what R68-7-19(7) targets.
- Use a nurse tank filled away from the water source when practical, so the sprayer is never connected to the source at all.
5. Container Rinsing
A container is not empty until it is rinsed by the labeled method. Both accepted methods put the rinsate into the spray tank, where it is applied as part of the labeled application.
| Method | Procedure | Notes |
|---|---|---|
| Triple rinse | Empty and let drain 30 seconds. Fill 10–20% with clean water, close, shake or rotate to contact all interior surfaces, pour rinsate into the spray tank, and drain 30 seconds. Repeat two more times. | Three separate rinses; the drain time is part of each cycle |
| Pressure rinse | Puncture the container, insert the pressure-rinse nozzle, and rinse for at least 30 seconds with the rinsate draining into the spray tank | One operation; the puncture also renders the container unusable, which prevents reuse |
After rinsing, containers must be handled as the label and 40 CFR Part 165 direct — typically recycling through an approved container program or disposal at an approved site. Do not reuse pesticide containers for any other purpose, burn them, or bury them.
6. Rinsate Is a Pesticide
Rinsate — the water from rinsing containers, tanks, and equipment — contains active ingredient and is legally a pesticide. The hierarchy for handling it:
- Best: use it as make-up water in the next tank of the same product, or apply it to a site on the label at or below labeled rates.
- Acceptable: store it in a labeled, sealed, dedicated rinsate container for use in a future compatible mix.
- Never: pour it on the ground, into a ditch, into a storm or floor drain, or into a septic system. Disposal at an unapproved location violates R68-7-19(6) and is an unlawful act under R68-7-20(30).
7. Mix Only What You Will Apply
The most reliable way to avoid a disposal problem is not to create one. Calculate the area accurately (Chapter 8), calibrate before mixing, and mix the amount that area requires. If leftover solution is unavoidable, apply it to a labeled site at labeled rates — that is a legal application, whereas dumping it is a violation.
8. Cleanup After the Job
- Rinse the interior and exterior of the equipment, capturing washwater on the pad or applying it to a labeled site.
- Clean nozzles, screens, and filters with a soft brush; never blow a plugged nozzle out with your mouth.
- Wash PPE separately from other laundry and wash gloves before removing them.
- Wash your hands and face before eating, drinking, using tobacco, or using the restroom, and shower and change clothing at the end of the day.
- Record the application within Utah's 24-hour window while the details are fresh.
An applicator fills a sprayer by placing the fill hose down inside the tank, below the surface of the spray solution, and walks away to check equipment. Which two hazards has this created?
Which description of triple rinsing is correct?
A crew has 40 gallons of leftover diluted spray solution at the end of the day. What is the correct disposition?
Why does the core manual recommend varying the location of a temporary mixing and loading site rather than always using the same spot?