Hazardous materials are transported in North America through millions of miles of underground pipelines. Products commonly transported through these pipeline systems include natural gas, crude oil, gasoline, diesel fuel, and jet fuel. Although the pipelines are buried, there are aboveground structures and signs indicating the presence of underground pipelines.

Liquid Pipelines

Surface indications of a liquid pipeline leak can include:

• Liquids bubbling from the ground
• “Oil slick” on flowing or standing water
• Flames that appear to be coming from the ground
• Vapor clouds

Structures – Storage Tanks, Valves, Pump Stations, Aerial Patrol Markers

Signs – Will often appear at road, railroad, and water crossings. Signs may also be posted at property boundaries. The signs will include the operator’s name, product transported, and an emergency phone number for the operator. Warning, Caution, or Danger will appear on the signs.

Gas Pipelines

Surface indications of a gas pipeline leak can include:

• Hissing, roaring, or blowing sound
• Dirt or water being blown in the air
• Continuous bubbling in wet or flooded areas
• Flames that appear to be coming from the ground
• Dead or brown vegetation in an otherwise green field
• In winter, melted snow over the pipeline

Gas Transmission pipelines are large-diameter, steel lines transporting flammable, toxic, or corrosive gas at very high pressure.

Structures – Compressor Station Buildings, Valves, Metering Stations, and Aerial Patrol Markers

Signs – Will often appear at road, railroad, and water crossings. Signs may also be posted at property boundaries. The signs will include the operator’s name, product transported, and an emergency phone number for the operator. Warning, Caution, or Danger will appear on the signs.

Natural gas Distribution pipelines are typically smaller-diameter, lower-pressure pipelines and may be steel, plastic, or cast iron. Natural gas is delivered directly to customers through distribution pipelines.

Regulator stations, customer meters & regulators, and valve box covers are generally the only aboveground indications of gas distribution pipelines.

Should you notice a leak or a spill, remember to only approach from upwind and uphill, identify the emergency telephone number for the company and then call that number as well as 911. Be cautious concerning the risks of asphyxiation, flammability as well as the danger of a potential explosion.

If you know the material involved, identify the three-digit guide number by looking up the name in the alphabetical list (blue-bordered pages) and then by using the three-digit guide number, consult the recommendations outlined in the recommended guide.