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Illegal Indoor Marijuana Cultivation (IMC)

Guidance on the recognition and response considerations for illicit indoor marijuana cultivations (IMC) also called grow house. 

Overview 

Indoor marijuana cultivations includes legal and illegal operations. They range from small-scale residential setups to large commercial facilities.  This guideline is primarily intended for illegal improvised grow operations commonly found single and multi-family residences. 

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PHOTO: Illicit IMC including bars on the widows. [Photo Copyright ER Playbook]

Exterior Indications of a Possible Illegal IMC  

  • Unusual buzzing sounds coming from inside the residence from light ballasts  
  • Presence or sounds of fans running 
  • Bright light emitting from cracks around windows and doors
  • Condensation collecting on windows
  • Blacked-out or heavily shaded windows
  • Security inconsistent with the neighborhood including windows and doors that are fortified, or extra locks on doors or gates
  • The absence of snow or frost on roofs or rooflines caused by the heat produced from grow lights
  • Heat visible from the roof using a thermal imaging camera
  • Skunk like odor
  • Electric utility meter tampered with

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Hazards

Illegal Indoor marijuana cultivation (IMC) operations contain multiple hazards, including chemical hazards, reduced oxygen environment, flammable gases, entanglement/trip hazards, structural modifications, improvised/overloaded electrical, bypassed electrical meters, mold, and criminal suspects.  Illicit operations may contain booby-traps or un secured weapons.  

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PHOTO: Illustration of common hazards. [Copyright ER Playbook]

Chemicals

Chemicals are frequently present in indoor grows include:

  • Fertilizers 
  • Herbicides 
  • Pesticides, including organophosphates  
  • Fungicides
  • Carbon Dioxide (CO2) compressed gas cylinders 
  • Carbon Dioxide (CO2) gas generators 
  • Sulfur burners/vaporizers 

Carbon Dioxide CO2 Gas Generator

Indoor marijuana cultivations often use increased carbon dioxide CO2  environments to enhance plant growth.  The additional CO2 can provided from compressed gas CO2 cylinders, propane-powered, or natural gas powered CO2 generators. Increased CO2 within these tightly sealed rooms can displace oxygen, leading to asphyxiation.

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PHOTO: Illustration of chemicals commonly found in illegal indoor marijuana cultivation operations and their hazards. [Copyright ER Playbook] 

Entanglement Hazards

  • Ventilation ducting
  • Exposed electrical wiring
  • Extension cords, 
  • Flexible plastic irrigation tubing 
  • Suspension ropes and cables 
  • Large-diameter flexible ducting

The ventilation ducting is often constructed of a lightweight aluminum foil laminate wrapped around small diameter helical wire. Under fire conditions, the exterior sheathing burns/melts away, leaving the helical wire exposed.  This presents a significant entanglement hazard for firefighters. 

Electrical Hazards

Illegal IMC can present a shock and electrocution hazards to responder from multiple sources including: 

  • Large number (20+) high-pressure sodium/metal halide or LED overhead lights  
  • Improvised or exposed electrical wiring
  • Open breaker panels 
  • Overloaded household circuits 
  • Overloaded extension cords or plug-strips
  • By-passed or altered electrical meter/power feed into the structure to reduce costs or avoid detection due to high energy use. 

Illegal marijuana cultivations can consume upwards of 10,000 to 12,000 kW hours of electricity per month, nearly 20 times average household use. 

Illegal tampering or by-passing the electrical meter could resulting in standard electrical disconnect/power shut-down procedures used to control utilities during a structure fire or emergency failing to actually shut down the power feeding into the structure. 

Mold

Mold in grow houses is a common issue driven by the high humidity (often 80%+) and moisture required for plant cultivation. 

Illegal IMC Recognition

When conducting reconnaissance at an unknown illicit lab to determine the lab type, evaluate the Propaganda, Precursors, Processes, and Products present (4 P's Method) to assist in recognizing the type lab.  Illegal indoor marrijuan cultivation operations may include the following: 

See Also Clandestine Lab Recognition Process. 

Propaganda and Modus Operandi

  • 420 references 
  • Marijuana and THC magazines 
  • Growing manuals and guides  

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Precursors and Supplies 

  • Carbon Dioxide cylinders or generators
  • Propane cylinders 
  • Sulfur generator or vaporizer
  • Pesticides and herbicides  
  • Plastic sheeting, plant stocks, fertilizer bags, plastic piping 
  • Large amount of soil and pots acquired or discarded 
  • Lumber or building supplies 

Process and Equipment

  • Agricultural chemicals (see chemical list above) 
  • High intensity lighting 
  • Irrigation pumps and hoses 
  • Ventilation systems and fans  
Products and Waste Produced
  • Marijuana plants 
  • A distinctive “skunk” or “rotten cabbage-like” odor of marijuana inside or emitting from the structure 
  • Used potting buckets or soil 
  • Discarded ventilation equipment or electrical wires 

See Also Marijuana / Cannabis 

Response Considerations 

HazMat Response Considerations 

Incident Managment 
  • Coordinate operations with law enforcement 
  • Ensure no suspects or aggressive animals are potentially in the lab
  • If any signs of booby traps are encountered, withdrawal and request bomb squad/hazardous device team support  
  • IC should consider the need to notify or coordinate with supporting agencies including building department, health department, environmental AHJ, or cannabis regulatory AHJ.  
  • Establish and mark control zones
  • Develop an incident action plan (IAP) and safety plan 
PPE Selection 
  • Consider Level B ensemble for initial recon and air monitoring. 
  • If a flammable hazard is suspected or encountered, don structural fire fighter protective clothing (SFPC) or fire resistance clothing and SCBA until hazard is abated. 
  • Downgrade PPE when safe to do so. 
  • Consider insulated electrical gloves depending on the degree of hazard 

Air Monitoring and Detection 

  • Radiation detection to rule out
  • O2 to check for oxygen displacement 
  • LEL for flammable 
  • PID 
  • Monitor for SO2 (consider using using an H2S electrochemical with correction factor if needed) 
  • CO2 monitor (do not rely on oxygen depletion alone for CO2 monitoring) 
  • Pesticide test kit  
  • Particulate monitor 
  • Detection papers 
Recon 
  • Identify hazards and conduct air monitoring 
  • Locate and turn off CO2 and SO2 generators 
  • Determine if any other illicit processes/productions are occurring 
  • Look for indications of illicit THC extraction process 
  • Identify chemicals and cylinders present 
Render Safe 
  • Ventilate the structure as needed 
  • Consider flaring any compromised propane cylinders 
  • Eliminate ignition sources 
  • Reduce entanglement hazard if possible 
  • Segregate, safely stage, or overpack and chemicals of concerns
  • Identify unknown chemicals 
  • Secure, tag the structure, and notify AHJ.  
Decontamination 
  • Consider dry decon method 
  • If pesticide contamination is significant, consider hybrid decon method.

Structure Fire Response

Some indoor marijuana grow  are discovered as a result of a structure fire response.  When responding to a structure fire in a suspected illegal indoor marijuana grow operation the fire department personnel should consider the following: 

Strategy Selection 

If a IMC is suspected during size up, the IC should consider if an offensive or defensive strategy is appropriate.  In addition to standard structure fire size up considerations, the IC should consider

Is this an occupied or unoccupied structure? 

Can electrical utilities be secured?

Have entanglement hazards been encountered? 

As soon as evidence of IMC is observed, ensure that all responding personnel and the dispatch center are notified over the incident’s command and tactical channels.
•    Broadcast an emergency alert tone notifying personnel of the hazards.
•    Request the electrical utility company respond to verify the building’s power has been isolated.
•    Using the above mentioned criteria, establish either an offensive or defensive strategy.
•    Following fire knockdown, continue to wear SCBA during overhaul operations. Due to the presence of fertilizers, herbicides, pesticides and sulfur emitters, use SCBA to reduce inhalation exposures.
•    Notify law enforcement for investigative follow up of possible criminal activity. Preserve related evidence and communicate your findings to fire investigators.

Request a HazMat team 

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