Dig safely and prevent utility dig-ins

Utility contacts can be costly – and deadly. Underground utility contacts cost utility owners and contractors millions of dollars in repair and service disruption costs every year. Not only that, but workers who contact buried utilities put themselves and the public at risk of injury or death. It’s your responsibility to dig safely to protect yourself, your crew and the public.

Always notify 811 well in advance of digging.
State law requires you to contact 811 by phone or online well in advance of digging or moving earth in any way – even for small jobs. This free service will notify member utilities near your dig site to mark the location of their underground lines so you can dig a safe distance away from them.

  • Massachusetts: Call 811 or 1-888-DIG-SAFE (344-7233) | digsafe.com
  • Metro New York, Long Island and the Rockaways: Call 811 or 1-800-272-4480 | NewYork-811.com
  • Upstate New York: Call 811 or 1-800-962-7962 | UDigNY.org

It’s the law!
If you don’t notify 811, you risk hitting an underground line. You or your coworkers could be hurt or killed, and you will be held liable for damages. You may also face criminal charges.

Pre-mark your dig area.
Before you contact 811, pre-mark your dig area with white paint, flags and/or stakes to help locators more easily identify and mark affected utilities. Document your markings with photos or video.

Always contact your state 811 center before digging and for the most current requirements.

Notify 811 well ahead of digging, so underground utilities can be marked and you can work safely.

Worker with jackhammer

Shocking factShocking fact:
Not all utilities are members of 811. You are responsible for notifying non-member utilities. For a list of these utilities, check with 811 in the state where you will be digging.

Wait for utility lines to be marked.
You must wait for National Grid and other utility companies to locate and mark their lines before you begin digging. The required wait times are below. (Allow more time for long, involved projects.)

  • Massachusetts: Wait at least 72 hours excluding weekends and legal holidays.
  • New York: Wait at least two full working days excluding the date of your call, weekends and legal holidays.

Check the site on your planned excavation date to confirm that your entire requested dig area has been located.


Shocking factShocking fact:
It is your responsibility to retain your 811 ticket number and related documentation. Keep this proof of compliance handy at the job site in case of emergency.

Utility locator marks protect you.
Make sure you and your crews understand how to read utility locator marks and know the American Public Works Association (APWA) uniform color code for marking underground utilities. Color code charts are usually available from your local 811 center.

Locator flags are placed within paint marks.
If you find flags outside the borders of locator marks, someone may have tampered with them. Contact 811.

Maintain the marks.
You are responsible for maintaining locator marks until your excavation is complete. Document marks with photos or video before you dig. If marks fade or are destroyed, stop work and notify 811 so the area can be located and marked again.

American Public Works Association Color Code for Locator Marks
Red Electric power lines
Pink Temporary survey markings
White Proposed excavation
Yellow Gas, oil or steam
Blue Potable water
Green Sewer and drain lines
Orange Communications lines, cables or conduit
Purple Reclaimed water, irrigation and slurry lines

Utility locator marks protect you from injury and prevent damage to underground utilities. Make sure you and your crews understand them.

Locator marks

National Grid flag marker

Shocking factShocking fact:
You might arrive at a job site and find no marks, even AFTER utility locating has been completed. If so, do not assume the area is clear of utility lines. Look for aboveground signs of unmarked utilities, such as gas or electric meters, pipeline markers, valves, etc. Also check for signs of something buried after the locate was completed, such as a fresh trench. If you find unmarked facilities, stop digging and notify 811.

The tolerance zone protects you and buried utilities.
The tolerance zone spans the width of a marked utility line plus a specified tolerance distance from each indicated outside edge – 24 inches in New York and 18 inches in Massachusetts. Digging with care in this zone helps protect you from utility line contacts – and helps protect utility lines from damage.

Use only hand tools in the tolerance zone.
For your safety, do NOT use mechanical excavation equipment within the tolerance zone. Use only hand tools or vacuum equipment.

Always contact your state 811 center before digging and for the most current requirements.

To avoid damaging buried utilities, do not power dig within the tolerance zone. Hand dig or use vacuum equipment instead.

Tolerance zones

Shocking factShocking fact:
The width of the tolerance zone varies from state to state, and it is the excavator’s responsibility to know what it is.

Check utility depth for yourself.
Before you can work safely near an underground utility, you must first verify its location. Flags and locator marks tell you the direction the utility is running, but not how deeply it is buried. The only way to be sure of utility depth is to carefully hand dig to expose the line and see it with your own eyes.

Proper hand-digging tools and techniques protect you and prevent utility line damage:

  • Use a blunt-nosed shovel to loosen the soil, and a regular shovel to remove it. Do not use a pickax or any sharp or pointed digging tools. Do not stab at the soil or stomp on the shovel with both feet.
  • Work with a gentle prying action and dig at an angle, so the shovel will slide along the surface of the wire, conduit, or pipe. Or, dig to the depth where you expect the utility line to be, but off to the side. Then use a prying motion to break away soil as you approach the utility laterally.
  • Be sure to dig until you find the actual utility line, not just tracer wire or warning tape.

Notify 811 if you cannot find a marked utility line. Locate marks may not be accurate. If you cannot visually verify the indicated line within the tolerance zone, stop work and call 811.

Before excavating near buried utility lines, always hand dig to verify their location.

Contractor hand digging

Shocking factShocking fact:
Buried utilities are supposed to be installed at a specified depth. But in reality, utility depth is unpredictable. Improper installation, landscaping, regrading, repaving, erosion and building development can all alter utility depth.

Vacuum equipment saves hand labor.
Vacuum technology can expose buried utilities without harming them. It uses suction and water pressure to remove soil down to the utility. Operate vacuum equipment only if you have been properly trained in its use.

If damage to a utility does occur, report it immediately. Repairs can be made more easily while the utility is still exposed. Never try to fix a damaged utility yourself.

Be sure to wear proper personal protective equipment when using vacuum technology to verify utility depth.

Vacuum excavator

Shocking factShocking fact:
Follow recommended practices for backfilling any utilities you uncover or expose with vacuum technology. Check with the local utility owner and municipality. Some facilities require a bed of sand, fine stone or slurry.

Know what's below. 811 before you dig.Notify 811 well in advance.
If you are planning to use directional drilling, notify the 811 center well ahead of the job. Let them know about the equipment you will be using, and ask them to space locator marks closer together. This will help you see if the utility’s path shifts or turns suddenly.

Dig potholes so you can safely monitor the drill head.
A buried drill head makes it impossible to tell how close you really are to an existing utility. This makes it especially important to manually expose the line and watch as the drill string passes through. Keep a margin of safety by planning the bore to be a minimum distance of 36 inches from the utility. Watch the drill head cross during the initial bore and also during backreaming to ensure this minimum distance is maintained.

Calibrate the bore head and locating device at the start of each job.
Remember, the locating device can monitor the bore head on the initial pass, but may not be able to monitor the backream head.

Stay at least three feet away when boring parallel to buried utilities. Pothole utilities so you can monitor the bore head path and visually verify a safe distance.

Drilling machine for trenchless pipelaying

Shocking factShocking fact:
Many drilling rigs have utility strike alarms that will alert you if you contact a buried power line. If this alarm sounds, assume you have hit a live power line and follow your company’s guidelines and the emergency procedures described on this website.

Markers indicate the general location of our high-pressure natural gas transmission pipelines.
These markers are usually found at roadways, railroad crossings and other points along the pipeline route. They are placed near pipelines but not necessarily on top of them, and pipelines may not follow a straight course between markers.

Pipeline markers and maps do not show gas distribution main lines or service lines.
Never use them as a substitute for notifying 811 to have all utility lines in your dig area located and marked.

Working within 15 feet of a National Grid high-pressure natural gas transmission pipeline or other critical facility requires special arrangements.
Prior to digging, you are required to attend an onsite meeting and/or have contact with qualified National Grid representatives to help reduce the risk of excavation-related damage. National Grid MUST be onsite during the excavation.

Yellow and black markers show the general location of our high-pressure gas pipelines.

Gas marker

Utility pole wrap pipeline marker

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You must support gas pipelines during excavation and backfill activities to avoid pipes being damaged by their own weight or soil compaction. Notify National Grid whenever cast-iron gas pipe is exposed or falls within an excavation trench’s angle of repose.

Natural gas utilities add a distinctive, sulfur-like odor to natural gas to help people detect leaks.
However, in some cases you may not be able to smell this odor. And gas in transmission pipelines may not be odorized.

Do not rely on your nose alone to detect a gas leak.
Use your senses of sight and hearing as well. Here are the signs:

  • A hissing, whistling or roaring sound as gas escapes from a pipe
  • Dirt blowing into the air from a hole in the ground
  • Continuous bubbling in water
  • Dead or dying vegetation (in an otherwise moist area) over or near a pipeline
  • A damaged connection to a gas appliance
  • Exposed pipeline after a fire, flood or other disaster

Use your senses of smell, sight and hearing to detect natural gas leaks.

Dirt blowing in air

Bubbling water

Dead vegetation

Exposed pipeline

Shocking factShocking fact:
You may not be able to detect the typical sulfur-like odor of natural gas if you have a diminished sense of smell, have been exposed to the same odor for too long or the odor is masked by other smells. Chemical and physical processes can also strip the odor from natural gas.

If you suspect a gas leak, take these steps immediately:

  • Assume there’s a danger.
  • Warn others and leave the area quickly. Do NOT wait for utility personnel to arrive. Leave your equipment behind.
  • Do NOT use matches, lighters or anything electrical (even a phone, garage door opener, or light switch) in the vicinity of the leak. A spark from any of these items could ignite leaking gas and cause an explosion.
  • Do not operate any gas pipeline valves or stop the flow of gas.
  • Leave the excavation open.
  • From a safe location, call 911 and National Grid. (See our gas emergency numbers at the bottom of this page.) Call even if damage appears minor.
  • Stay away from the area until National Grid personnel say it is safe to return.
  • Report the incident to your supervisor.

Smell Gas. Act Fast.

If you suspect a gas leak, act fast. Do NOT assume someone else will report it.

Do not use light switch

Shocking factShocking fact:
Leaking natural gas can be ignited by a tiny spark or flame – even a lit cigarette.

There’s no such thing as minor damage to gas lines.
What looks like a small nick in a gas line can result in a major health and fire hazard to the surrounding neighborhood. Even just nicking the coating on a gas pipeline or cutting a tracer wire can cause the line to fail or become unlocatable in the future.

Report all pipeline contacts.
Any time you contact a natural gas pipeline, assume there’s a danger. Warn others, leave the area immediately and call 911 and National Grid from a safe location. Report the incident to your supervisor as well.

Never bury a damaged gas pipeline.
Trying to cover up an accident can be dangerous, and can lead to costly damages or criminal charges against you and your company.

Any time you contact a natural gas pipeline, assume there’s a danger. Call 911 and National Grid.

Construction worker on cellphone

Shocking factShocking fact:
Scraping or nicking the coating on a gas pipeline can accelerate corrosion and increase the potential for a gas leak.

If your equipment contacts a buried power line, take these steps:

  • Move equipment away from the line if you can do so safely.
  • Have someone call 911 and National Grid immediately.
  • Stay on the equipment until National Grid utility workers signal you off.
  • Warn others away from the line and anything it is touching. Anyone who touches the equipment or even the ground nearby may be injured or killed.

If fire or other danger forces you off:
Jump clear without touching equipment and the ground at the same time. Land with your feet together and shuffle away with small steps. Once clear, do not return to the equipment until National Grid has declared it safe.

In the event of a power line contact, take appropriate safety steps and notify 911 and National Grid immediately.

Worker jumping clear of equipment

Shocking factShocking fact:
When equipment contacts a line, electricity spreads out in the ground like ripples in a pond, and the voltage decreases with distance from the point of contact. If your legs bridge two areas of different voltage, electricity could travel through them, causing a serious or fatal shock. This is why you should never run or take long steps in the vicinity of a power line contact.

Contractor hand digging