9.2 Mixing/Loading Operations, Container Rinsing & Disposal Protocols
Key Takeaways
- Mixing and loading operations present the highest statistical risk of acute applicator poisoning and concentrated point-source environmental contamination due to handling undiluted chemical concentrates.
- Colorado requires a mixing and loading pad once a site handles 500 gallons of liquid pesticide product, 3,000 pounds of dry product, or 1,500 pounds of active ingredient in any one-year period, sized under 8 CCR 1206-1 to hold 125% of the largest container loaded or unloaded when unprotected from precipitation, or 110% when protected; field mixing and loading is exempt.
- Water sources must be protected against back-siphoning by maintaining an absolute physical Air Gap (vertical distance equal to at least 2 times the inside diameter of the supply pipe, minimum 1 inch above tank rim) or installing an approved Reduced Pressure Zone (RPZ) backflow assembly.
- A closed transfer system is required when the product labeling requires one — 40 CFR § 170.607(d) makes the agricultural employer provide it in that case — and uses suction extraction probes, dry-disconnect couplings, and automated container rinsing to eliminate handler exposure and aerosol emissions.
- Empty rigid pesticide containers must be immediately decontaminated via Triple-Rinsing or Pressure-Rinsing, punctured to prevent reuse, and recycled through the Ag Container Recycling Council (ACRC) or disposed of in approved sanitary landfills; open burning or burying containers is strictly illegal.
9.2 Mixing/Loading Operations, Container Rinsing & Disposal Protocols
Critical Operational Phase: More than 80% of all acute pesticide poisonings and catastrophic point-source groundwater contamination events occur during the mixing and loading phase. Handlers are exposed directly to raw, undiluted chemical concentrates—substances that are 100 to 1,000 times more concentrated than the final diluted spray mixture. Under FIFRA Section 19, 40 CFR Part 165, and Colorado 8 CCR 1203-2, applicators must adhere to stringent containment, backflow prevention, container decontamination, and waste management mandates.
1. Mixing and Loading Pad Engineering & Containment
Repeatedly mixing and loading spray equipment on bare ground or gravel creates high-risk point-source contamination. Decades of small drips, hose disconnects, and washdown water can saturate the soil, migrating downward into shallow aquifers or washing into nearby surface waters during storm events.
Permanent Containment Pad Specifications
Commercial applicator facilities, custom applicators, and high-volume agricultural operations must conduct all mixing, loading, and equipment washing on a permanent, engineered mixing and loading containment pad:
┌─────────────────────────────────────────────────────────────────────────────┐
│ PERMANENT MIXING/LOADING PAD ENGINEERING DESIGN │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ 1. WATERTIGHT REINFORCED CONCRETE: High-strength, steel-reinforced slab │
│ coated with a seamless chemical-resistant epoxy or polyurea sealant. │
│ │
│ 2. MINIMUM VOLUMETRIC CAPACITY (Colorado, 8 CCR 1206-1): │
│ • 125% of the volume of the LARGEST CONTAINER to be loaded or │
│ unloaded if the pad is UNPROTECTED from precipitation, OR │
│ • 110% of that volume if the pad IS PROTECTED from precipitation. │
│ │
│ 3. SLOPED SURFACE & RECOVERY SUMP: Pad surfaces must slope uniformly │
│ (minimum 1% to 2% grade) toward a central or perimeter collection sump. │
│ │
│ 4. CHEMICAL RECOVERY PUMP: Sump equipped with an automated or manual │
│ explosion-proof pump to transfer spilled mix or washwater into labeled │
│ holding tanks for use as spray makeup water. │
│ │
│ 5. NO SEWER OR GROUND DISCHARGE: Sump must NEVER contain a gravity │
│ drain line connected to septic tanks, sanitary sewers, or storm ditches.│
│ │
└─────────────────────────────────────────────────────────────────────────────┘
Field Mixing & Portable Containment
When mixing must be conducted in the field away from permanent facilities:
- Site Selection: Choose a new, uncompacted location within the labeled target application site for each fill, rotating sites across the season.
- Distance Setbacks: Always mix at least 100 feet down-gradient from any wellhead, stream, irrigation ditch, wetland, or livestock water tank.
- Portable Containment Mats: Utilize portable, drive-in vinyl or polyurethane bermed containment berms ("duck ponds") beneath the spray tank and chemical jugs to catch drips during concentrate transfer.
2. Water Source Protection & Anti-Backflow Engineering
Back-siphoning occurs when a sudden drop in water supply pressure (e.g., a well pump failure, nearby hydrant opening, or main break) creates negative atmospheric pressure, drawing pesticide spray mixture backwards through the fill hose directly into the drinking water well or municipal distribution main.
┌─────────────────────────────────────────────────────────────────────────────┐
│ MANDATORY ANTI-BACKFLOW PROTECTIONS │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ METHOD 1: PHYSICAL AIR GAP (THE GOLD STANDARD) │
│ │
│ Fill Hose / Supply Pipe │
│ │ │
│ │ │
│ ▼ │
│ [=====] ◄─── Discharge End │
│ │ │
│ │ ▲ AIR GAP DISTANCE: │
│ │ │ Must be at least 2x the inside diameter of the │
│ │ │ supply pipe (minimum 1.0 inch absolute clearance) │
│ │ ▼ above the highest flood level / rim of the tank. │
│ ┌──┴──┐ │
│ ─────┘ └───── ◄── Top Rim / Flood Level Rim of Spray Tank │
│ │ │ │
│ │ Pesticide Tank │ (Hose must NEVER touch or enter the tank opening!) │
│ └─────────────────┘ │
│ │
│ METHOD 2: MECHANICAL BACKFLOW PREVENTERS │
│ • Reduced Pressure Principle (RPZ) Backflow Assembly: Required on all │
│ direct municipal water connections; tested and certified annually. │
│ • Double Check Valve Assemblies: Used for low-hazard non-potable lines. │
│ │
└─────────────────────────────────────────────────────────────────────────────┘
[!WARNING] The Deadly Submerged Hose Trap: Applicators must never submerge the end of a water fill hose below the liquid surface inside a pesticide spray tank. Submerging the hose creates a direct hydraulic connection. If water pressure drops for even two seconds, hundreds of gallons of toxic pesticide mixture will be sucked instantly into the aquifer or municipal water system, contaminating drinking water for entire communities.
3. Closed Transfer Systems — Required When the Label Says So
A Closed Transfer System (CTS) is an engineered mechanical system that extracts liquid pesticide concentrate from its original shipping container, meters the exact dose, and transfers it directly into the spray mix tank without exposing the handler or releasing chemical vapors into the atmosphere.
Core Components and Functionality
- Sealed Suction Extraction Probes: Specialized dry-lock probes inserted through the container cap or container wall that lock onto internal dip tubes.
- Dry-Disconnect Couplings: Spring-loaded valved fittings that automatically seal shut before hoses can be disconnected, ensuring zero chemical drip.
- Integral Container Rinsing: Integrated high-pressure water injectors that automatically triple-rinse the empty pesticide jug from the inside while the closed probe remains attached, discharging the rinsate directly into the mix tank.
When is a closed system actually required? The trigger is the product labeling, not a toxicity category. Under the Worker Protection Standard at 40 CFR § 170.607(d), the agricultural employer must provide a closed system to handlers when the pesticide labeling requires one — and it is the labeling that names which products those are, commonly including certain highly toxic organophosphates, metam sodium, and paraquat. There is no general federal or Colorado rule requiring a closed transfer system for every Toxicity Category I restricted use pesticide, so do not assume the signal word alone dictates the equipment. When using an approved CTS, handlers may be permitted by the label to reduce certain burdensome PPE (such as wearing chemical-resistant gloves instead of a full chemical-resistant suit and respirator), provided all required PPE is immediately available on site for emergency leak response.
4. Rigid Container Decontamination: Triple-Rinsing vs. Pressure-Rinsing
Under federal and Colorado law, an unrinsed pesticide container is classified as hazardous chemical waste. Disposing of unrinsed containers in a municipal landfill, open dump, or recycling facility is illegal and dangerous. Once a rigid container has undergone approved decontamination, it is legally classified as solid non-hazardous waste and is eligible for recycling or standard sanitary landfill disposal.
┌─────────────────────────────────────────────────────────────────────────────┐
│ TRIPLE-RINSING STEP-BY-STEP PROTOCOL │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ STEP 1: DRAIN CONCENTRATE │
│ • Empty container into spray tank; hold in vertical draining position for │
│ 10 to 30 seconds until continuous flow slows to individual drips. │
│ │
│ STEP 2: ADD CLEAN WATER CHARGE │
│ • Fill container 1/4 to 1/3 full with clean water (e.g., add 0.5 to 0.8 │
│ gallons of water to a standard 2.5-gallon jug). │
│ │
│ STEP 3: SECURE CAP & SHAKE VIGOROUSLY │
│ • Replace cap tightly; shake vigorously for 30 seconds, rotating the jug │
│ so water contacts all interior surfaces, neck, handle, and corners. │
│ │
│ STEP 4: DRAIN RINSATE INTO MIX TANK │
│ • Pour rinsate into the spray mix tank; allow to drain for 10 to 30 seconds│
│ to ensure all rinsate serves as makeup water for the spray solution. │
│ │
│ STEP 5: REPEAT TWO MORE TIMES (3 COMPLETE CYCLES TOTAL) │
│ • Repeat Steps 2 through 4 two additional times. │
│ │
└─────────────────────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────────────────┐
│ PRESSURE-RINSING STEP-BY-STEP PROTOCOL │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ STEP 1: DRAIN CONCENTRATE │
│ • Empty the container completely into the spray tank, holding vertically │
│ for 10 to 30 seconds until flow reduces to drips. │
│ │
│ STEP 2: INSERT PRESSURE-RINSE PROBE │
│ • Hold container upside down over the spray tank opening. Push the sharp, │
│ pointed pressure-rinse probe through the side or bottom of the jug. │
│ │
│ STEP 3: FLUSH UNDER WATER PRESSURE │
│ • Activate clean water supply at 30 to 50 psi for at least 30 seconds. │
│ • Rotate probe tip so high-velocity spray washes all interior walls, the │
│ handle cavity, and cap threads. │
│ │
│ STEP 4: COMPLETE DRAINAGE │
│ • Allow all rinsate water to drain directly into the spray mix tank. │
│ │
└─────────────────────────────────────────────────────────────────────────────┘
Comparison of Rinsing Methodologies
| Feature / Metric | Triple-Rinsing | Pressure-Rinsing |
|---|---|---|
| Time Required | 3 to 5 minutes per container | 30 to 60 seconds per container |
| Water Efficiency | Uses 1/4 to 1/3 volume $\times$ 3 charges | Continuous flow at 30–50 psi (lower total water volume) |
| Equipment Needed | Clean water supply, container cap | Sharp pressure-rinse nozzle attached to pressurized hose |
| Cleaning Efficacy | Removes >99.99% of chemical residue | Removes >99.99% of chemical residue; superior on viscous pastes |
| Puncturing Action | Must be manually punctured afterward | Automatically punctures container during probe insertion |
5. Container Rendering, Recycling & Disposal Mandates
Once a rigid container has been thoroughly triple-rinsed or pressure-rinsed, it must be permanently decommissioned to prevent human reuse.
Mandatory Container Puncturing
Immediately after rinsing, the applicator must puncture the bottom and sidewalls of the plastic container using a utility knife, axe, or the sharp tip of a pressure-rinse nozzle. Puncturing achieves two critical legal and safety objectives:
- It renders the jug permanently incapable of holding liquids, eliminating the risk that farmworkers, children, or the public will reuse the container to store drinking water, food, fuel, or livestock feed.
- It signals to landfill operators and recycling inspectors that the container has been properly decontaminated.
Ag Container Recycling Council (ACRC) Program
Clean, punctured High-Density Polyethylene (HDPE #2) pesticide jugs should be recycled through the Ag Container Recycling Council (ACRC) program or state-sponsored agricultural collection drives (such as those coordinated by the CDA and Colorado CSU Extension). Recycled HDPE jugs are granulated and manufactured into industrial non-food products, including corrugated highway drainage pipes, fence posts, marine pilings, and industrial pallets.
To prepare jugs for ACRC recycling collection:
- Ensure container is 100% clean and dry (no caked chemical residue on neck or walls).
- Remove all plastic caps, booklets, foil induction seals, and neck labels (caps and paper booklets cannot be processed in standard HDPE recycling extruders).
- Place cleaned, un-capped, punctured jugs into collection bags or trailers.
Approved Sanitary Landfill Disposal
If recycling options are unavailable in remote Colorado counties, clean, decontaminated, and punctured containers may be legally disposed of in an approved municipal solid waste sanitary landfill (Subtitle D landfill). Applicators must check with local landfill operators prior to disposal, as some facilities require advance notice or specific waste delivery manifests.
Prohibited Disposal Practices
┌─────────────────────────────────────────────────────────────────────────────┐
│ STRICTLY PROHIBITED DISPOSAL PRACTICES │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ ❌ OPEN BURNING: Burning pesticide containers, paper bags, or packaging is │
│ a severe felony under the Colorado Clean Air Act (C.R.S. Title 25) and │
│ CDA regulations. Burning releases extremely toxic dioxins, furans, │
│ phosgene, hydrogen chloride, and heavy metal vapors that drift onto │
│ neighbors, livestock, and crops. │
│ │
│ ❌ ON-SITE BURIAL: Burying chemical containers, surplus concentrates, or │
│ rinsates on farm property or public land is strictly illegal under │
│ RCRA and Colorado hazardous waste laws. Buried plastics degrade slowly, │
│ leaking concentrated toxins directly into groundwater tables. │
│ │
│ ❌ REUSE OF CONTAINERS: Reusing empty pesticide jugs for storing drinking │
│ water, diesel fuel, motor oil, cooking oil, or animal feed is illegal │
│ and has resulted in numerous fatal human and livestock poisonings. │
│ │
│ ❌ SEWER DUMPING: Pouring leftover spray mix, concentrates, or rinsates │
│ into sinks, storm sewers, floor drains, or septic systems is a federal │
│ violation of the Clean Water Act and local municipal ordinances. │
│ │
└─────────────────────────────────────────────────────────────────────────────┘
6. Excess Spray Mixture & Rinsate Management
The most effective way to eliminate pesticide waste is accurate calibration and precise tank-mix volume calculation so that zero excess spray mix remains after treating the target site.
Legal Application of Excess Tank Mixture
If leftover spray mixture remains in the tank upon completing an application, the applicator must:
- Apply to Labeled Site: Apply the remaining dilute mixture to a registered, labeled target site or crop listed on the container label.
- Observe Maximum Rate Limits: The total active ingredient applied to the site (initial application plus leftover spray) must never exceed the maximum labeled application rate per acre per season.
Proper Utilization of Equipment Wash Water and Rinsates
When rinsing spray booms, tanks, and nozzles between chemical jobs:
- Collect Rinsate: Collect all interior boom flushes and tank rinsates on the containment pad or directly into dedicated collection drums.
- Use as Future Makeup Water: Store the rinsate in clearly labeled tanks (e.g., "Glyphosate Tank Rinsate — 2% Dilution") and use it as makeup water for subsequent spray batches of the same pesticide on an approved labeled crop.
- Avoid Incompatible Carryover: Never use herbicide rinsate as makeup water when preparing an insecticide or fungicide batch for sensitive broadleaf crops or ornamental turf, as minute herbicide residues will cause severe non-target crop death.
When filling a 500-gallon pesticide spray tank from a municipal water line or agricultural well, what is the mandatory physical Air Gap requirement to prevent catastrophic back-siphoning?
During the standard Triple-Rinsing procedure for a 2.5-gallon rigid plastic pesticide jug, what volume of clean water must be added for each rinse cycle, and how long must the container be shaken?
Why is the open burning of empty plastic or paper pesticide containers strictly prohibited under Colorado state environmental laws and CDA regulations?
What is the primary operational and legal purpose of immediately puncturing the bottom and sidewalls of a rigid plastic pesticide jug after completing triple-rinsing?