Searching for a Home? What You Need to Know About Buried Petroleum & Hazardous Liquid Pipelines

When searching for your next home, you’re probably thinking about kitchens, yards, school districts, lot size, and curb appeal. But the recent BP (Olympic Pipeline) hazardous liquid pipeline leak in east Everett is a reminder that there’s one factor homebuyers rarely consider — whether a petroleum or hazardous-liquid pipeline runs near the property.

In late 2025, BP confirmed that its Olympic Pipeline had been leaking fuel underground just east of Everett, near the Snohomish River and close to residential areas, environmentally sensitive zones, and within miles of major commuter corridors.

Cleanup operations have involved removing contaminated soil, monitoring groundwater, and temporarily shutting down part of the pipeline system.

Several state agencies — including the Department of Ecology — have been involved in oversight and investigation.

The Olympic Pipeline system stretches more than 400 miles and runs through Snohomish County, Skagit County, and King County, supplying fuel to airports (including SEA), refineries, and distribution centers. This means many buyers in our region — especially in communities like Everett, Snohomish, Marysville, Lake Stevens, Mount Vernon, Burlington, and Arlington — may live near a major petroleum pipeline without realizing it.

While incidents like this are not frequent, they do happen, and they highlight the importance of understanding what pipelines transport, where they are located, and how to evaluate whether proximity to one should influence your buying decision.

This guide breaks down everything you need to know before you buy.

What Are Petroleum & Hazardous Liquid Pipelines?

These pipelines transport liquid petroleum products, including:

• Gasoline

• Diesel

• Jet fuel

• Crude oil

• Natural gas liquids (NGLs)

• Refined petrochemical products

These are large, high-capacity pipelines, very different from the small gas lines that serve individual homes.

Hazardous-liquid pipelines can run:

• Along major utility corridors

• Beneath farmland and rural land

• Near or under highways

• Through or behind residential neighborhoods

They’re typically buried several feet underground and cross private land via recorded utility easements.

In Snohomish and Skagit Counties, the Olympic Pipeline is one of the largest and best-known hazardous-liquid pipelines. The BP Olympic Pipeline is typically buried between 3 and 4 feet (36 to 48 inches) underground. However, there is no single "average" depth for the entire 400-mile system because the depth varies significantly depending on what is above the ground. Based on easement agreements and safety manuals specific to the Olympic Pipeline, here are the standard depth requirements:

• Standard Terrain (Fields/Open Land)

  • The pipeline is usually buried with a minimum of 3 feet (36 inches) of cover.
    

• Road Crossings

  • Under roads and highways, it is buried deeper, typically requiring a minimum of 5.5 feet (66 inches) of cover to protect it from traffic vibration and construction.
    

• Drainage Ditches

  • It is generally buried at least 4 feet (48 inches) deep when crossing drainage ditches to prevent damage from maintenance equipment.
    

• Agricultural Areas

  • In some farming areas, you may find it buried between 3.5 and 4 feet to allow for safe plowing, though deep ripping equipment can still pose a risk.

What Are the Risks of Living Near a Liquid Pipeline?

While serious incidents are rare, buyers should be aware of the potential impacts:

1. Leaks or Spills

Accidental releases — like the one recently discovered east of Everett — can contaminate:

• Soil

• Groundwater

• Surface water (streams, wetlands, rivers)
  

Cleanup operations can be extensive and may involve:

• Heavy equipment

• Soil removal

• Groundwater monitoring

• Access to private property
  

2. Safety Zones & Emergency Access

Large pipelines typically include buffer zones along their easements where:

• Buildings cannot be constructed

• Trees cannot be planted

• Digging may require special permission

• The pipeline operator must have access for maintenance or emergency response
  

These limitations will appear on title records.

3. Noise, Access, or Maintenance Traffic

Residents near the Olympic Pipeline system and other large lines may occasionally notice:

• Utility crews performing maintenance

• Mowed or tree-cleared corridors

• Valve inspections or aerial monitoring

• Temporary equipment access
  

These are normal parts of regulated pipeline operations.

4. Impact on Resale Value

Homes directly on a hazardous-liquid pipeline easement may:

• Require special disclosures

• Appeal to a smaller pool of buyers

• Experience longer market times
  

This doesn’t automatically make them bad investments — but buyers should be informed.

What to Look for When Touring a Property In Person

Even before checking online maps, you can spot clues that indicate a pipeline corridor:

1. Pipeline Marker Signs

These are the most obvious indicator.

Look for:

• Yellow, orange, or white signs

• Round metal markers

• Labels such as “Petroleum Pipeline”, “Hazardous Liquid Pipeline”, or the operator name (e.g., BP, Olympic Pipeline Company, Marathon, Kinder Morgan)
  

By law, markers must appear where pipelines cross roads or public rights-of-way.

2. Wide, Cleared Utility Corridors

Hazardous-liquid pipelines often run beneath:

• Straight grassy strips

• Tree-free zones

• Mowed pathways between neighborhoods

• Open corridors behind multiple homes
  

This corridor is maintained for safety and emergency access.

3. Access Roads or Utility Gates

Watch for:

• Gravel or dirt maintenance roads

• Locked utility access gates

• Signs with emergency phone numbers or operator branding
  

These often indicate major underground infrastructure.

4. Utility Boxes or Above-Ground Appurtenances

You may occasionally see small structures related to pipeline operations:

• Valve sites

• Pressure monitoring stations

• Cathodic protection equipment
  

These can indicate a pipeline nearby.

How To Check for Hazardous Liquid Pipelines Online

Before making an offer, use these tools to confirm whether a pipeline is nearby — especially in Snohomish or Skagit County.

1. National Pipeline Mapping System (NPMS)

The most important tool for homebuyers.

The NPMS Public Viewer shows:

• Major hazardous-liquid pipelines

• Pipeline operators

• Product types

• Emergency contacts

  • Access online here or download the app from the app store. I found the app to be easier to use and zoom in. Though zooming in to a specific property can be a bit tricky, it can be done.

    
    

Search by:

• Address

• ZIP code

• County

  
  

This is essential for identifying high-volume transmission pipelines.

Following are map images as they appear on within the NPMS app. You can zoom in closer to a specific property.

NPMS App - Skagit County Hazardous Pipeline Mapping

NPMS App - Snohomish County Hazardous Pipeline Mapping

NPMS App - King County Hazardous Pipeline Mapping

2. County or City GIS Maps

Counties like Snohomish, King, and Skagit provide GIS mapping systems showing:

• Utility easements

• Right-of-way corridors

• Parcel boundaries

• Flood zones and environmental overlays

• Public infrastructure
  

These tools help you understand whether:

• A pipeline easement crosses the property

• The home backs up to a major utility corridor

• There are land-use restrictions

3. Property Title Report

During the purchase process, the title company will provide a preliminary title commitment listing:

• Recorded pipeline easements

• Easement width

• Operator rights of access

• Setback or safety limitations

• Recorded surveys or plats referencing utility corridors
  

If a hazardous-liquid pipeline crosses the property, it will almost always appear here.

4. Contact the Pipeline Operator

If the NPMS or GIS tools show a pipeline nearby, you can reach out directly to the operator (e.g., BP/Olympic) to ask:

• What the pipeline carries

• The depth of cover

• Age and condition

• Inspection and monitoring practices

• Emergency response planning

• Easement and access details
  

Operators are required by law to provide safety information to residents.

Don’t Skip the Home Inspection

A good home inspector should:

• Identify visible pipeline markers

• Recognize easements and utility corridors

• Flag suspicious above-ground features

• Recommend reviewing GIS or NPMS maps

• Point out safety or access concerns

  
  

While they won’t identify the exact pipeline product, they can alert you to unusual conditions of major transmission pipelines that are within close proximity to a home.

Final Thoughts: Should a Pipeline Stop You From Buying?

Not necessarily.

Petroleum and hazardous-liquid pipelines are heavily regulated and critical to Washington’s energy infrastructure. But recent events — like the Olympic Pipeline leak in Everett — show why homebuyers should be aware of:

• What pipelines carry

• Where they run

• What easements restrict

• What risks and safety considerations exist

• How proximity may impact future resale

With the right information, you can confidently evaluate whether a home near a pipeline aligns with your comfort level, safety expectations, and long-term plans.

Thank you for reading this blog. If you have any questions or need help assessing a home and proximity to a pipeline, I'd be happy to help. You can reach me here.

-Joe