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. 

PHOTO: Iliict IMC including bars on the widows. [Source Unknown]

Exterior Indications of an Illegal GrowIMC  

• Unusual buzzing sounds coming from inside the residence
• 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
  

Hazards

Illegal Indoor marijuana cultivation (IMC) operations contain multiple hazards, including chemicals, entanglement risks, structural modifications, improvised/overloaded electrical, bypassed electrical meters, mold, and criminal suspects.  

PHOTO: AI illustrationIllustration of common hazards. [Copyright ER Playbook]

Chemicals

Chemicals are frequently present in indoor grows.grows include:

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

CO2

CO₂ Gas Generator 

Also concerning is the presence of pressurized CO2CO₂ cylinders and propane-powered CO2CO₂ generators. Increased CO2CO₂ within these tightly sealed rooms can displace oxygen, leading to asphyxiation.

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

Entanglement Hazards

Numerous entanglement hazards exist. Among these are ventilation ducting, exposed electrical wiring, electrical cords, flexible plastic irrigation tubing, and roperope. (figure 3). Of particular concern is large-diameter flexible ducting, which is used in conjunction with inline ventilation fans for both intake and exhaust of air, heat and moisture from grow rooms (figure 4).rooms. This ducting, constructed of a lightweight aluminum foil laminate wrapped around small diameter helical wire, is notorious for entangling firefighters. Under fire conditions, the exterior sheathing burns/melts away, leaving the helical wire exposed. In a smoke-filled environment, these entanglement hazards can be difficult to detect.

Electrical Hazards

One of the most significant indoor grow-related hazards is the potential for electric shock. Due mainly to lighting needs, IMC residences use an astounding amountastoundamount of electricity. Each high-pressure sodium/metal halide light uses between 500 and 1,000 watts each, with a typical residential grow containing anywhere from 10 to 40 overhead lights (figure 12).lights. One of these homes can consume upwards of 10,000 to 12,000 kW hours of electricity per month, nearly 20 times average household use! In addition, electrical equipment may be poorly wired and the home’s circuits overloaded, leading to potential shock and fire ignition sources.

PHOTO: Improvised electrical set-up in a grow house.  [Photo by Fairfield Police Department]

Overloaded Electrical Systems 

Ballasts for lighting 

By Passed Electrical Meters

Illegal marijuana grow houses frequently bypass electrical meters to power intensive, 24/7 agricultural equipment (high-intensity lights, fans, irrigation pumps) without generating high-usage utility bills that might alert authorities

Of great concern are bypassed electrical meters. Due to either fear of detection by electric utility company employees or in wanting to avoid paying high electricity bills, growers will bypass electrical meters. As a result, personnel at an IMC fire may secure electrical utilities only to discover there is still power to the residence. If responders make contact with exposed wiring or spray hose streams onto energized equipment, there is a risk of electrocution.

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 

See Also Clandestine Lab Recognition 

Propaganda and Modus Operandi

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

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

Exterior Indicators  

• Unusual sounds coming from inside the residence (these are caused by grow light ballasts and sound similar to the humming of a utility pole-mounted transformer)
• Bright light emitting from cracks around windows and doors
• Condensation collecting on windows (caused by high humidity in grow rooms)
• Blacked-out or heavily shaded windows that are never opened
• Windows and doors that are fortified with security bars not in character with the neighborhood
• Extra locks on doors or gates that normally wouldn’t require it
• The absence of snow or frost on roofs as compared to similar homes or rooflines caused by the heat produced from grow lights
• Modified electrical meter 

Interior Indicators 

Products and Waste Produced

• A distinctive “skunk” or “rotten cabbage-like” odor of marijuana inside or emitting from the structure 

Response Considerations 

Structure Fire Response

Some IMC are discovered as a result of a structure fire response. 

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 

HazMat Response Considerations 

PPE Selection 

Insulated electrical gloves 

Air monitoring and detection 

Monitor for SO2 (consider H2S cross sensitivity) 

CO2 monitor 

Pesticide testing 

CO2 

Locate and turn off generators 

Sulfur generator 

CO2 generators 

Identify and Assess Cylinders 

Decontamination