Pipeline Integrity Management  

Integrity Management is the result of a Federal law that came from passage of the Pipeline Safety Improvement Act of 2002. Among other things, the law requires that the operators of transmission pipelines perform thorough evaluations of pipelines in High Consequence Areas.

What is a high consequence area?

A High Consequence Area (HCA) is an area located within close proximity of a transmission pipeline (generally less than 660 feet away) that is an area of common congregation, highly populated area, or a facility having persons that may be difficult to evacuate. Generally, in the first two cases, the areas must have 20 or more people, 50 or more times per year. Alaska Pipeline Company (APC), a subsidiary of SEMCO Energy, Inc. maintains more than  80 high consequence areas that totaled more than 29 miles in length. These areas are found across more than 400 miles of transmission pipeline spanning from Beluga to Anchor Point.

What kinds of evaluations must be performed on the pipelines?

Federal law provides several methods for operators like Alaska Pipeline Company (APC) to evaluate and test their pipeline system, for example:

  1. Operators may use in-line inspection tools (commonly referred to as “pigs”) that are bullet-shaped tools which travel through the pipeline recording information about the conditions of the pipe.
  2. Operators may also hydrostatically test a pipeline, in which case the pipeline is filled with water to a pressure 1.5 times that at which it normally operates.
  3. Operators may perform Direct Assessment of the pipeline, which includes an electrical evaluation of the pipeline, coating evaluation, and pipeline data aggregation. This method involves electrical current and coating surveys performed over the buried pipeline and then digging in several locations of the survey to confirm findings and evaluate the condition of the pipeline.
  4. Operators may also use “Other Technologies” that may be offered from pipeline experts and vendors that must be approved by Pipeline Hazardous Materials Safety Administration (PHMSA) prior to implementation.

In each case of evaluation, if the pipeline is not in satisfactory condition, repairs are made to ensure the pipeline's safe and continuous operability.

What is APC doing for Pipeline Integrity Management?

APC continues to work diligently in performing evaluations and inspections of its transmission pipeline system and making repairs accordingly. APC has successfully completed the baseline assessment of its HCA mileage and has begun performing periodic reassessments. As a matter of prudence, APC inspects and repairs many miles of pipeline in addition to the required HCAs to help ensure the safe and continuous operability of its system.

Where can I get more information about Integrity Management?

The United States Department of Transportation is responsible for oversight on Integrity Management, specifically the Pipeline and Hazardous Materials Safety Administration (PHMSA). Information regarding Integrity Management can be found at their website: http://primis.phmsa.dot.gov/gasimp/. Any inquiries regarding Integrity Management, or for additional information about APC and ENSTAR's Integrity Management Program, you may contact ENSTAR's Engineering Department at (907) 334-7740.

Click here to view ENSTAR's Pipeline Safety brochure

Safety Requirements For Excavation  

Excavation Requirements (Adobe PDF)

  1. Safety
  2. Pipeline Reliability
  3. Pressure Classification
  4. Recognizing ENSTAR‘s Pipelines
  5. Excavation Requirements
  6. Pipeline Components
  7. What to do if you damage a gas line
  8. Qualified Personnel Requirements


ENSTAR Natural Gas Company provides natural gas service through 3,100 miles of gas mains to over 131,000 customers in South Central Alaska. ENSTAR’s gas pipeline system is designed, installed, and maintained with the highest regard for safety in compliance with applicable federal, state, and local government statutes and regulations. ENSTAR is regularly inspected to ensure that its operation meets industry standards.

The US Department of Transportation Office of Pipeline Safety (DOT) oversees minimum safety regulations for the transportation of natural gas by pipelines. The DOT safety regulations are currently published in Title 49, Part 190, 191, 192 & 199 of the Code of Federal Regulations (CFR).

As an operator of a natural gas system, ENSTAR is required by the DOT regulations to:
1. Deliver gas safely and reliably to customers.
2. Provide training and written instruction for employees.
3. Establish written procedures to minimize hazards resulting from gas pipeline emergencies.
4. Keep records of inspections and testing.
5. Test employees in safety-sensitive positions for prohibited drugs and alcohol.

Pipeline Reliability

Natural gas pipelines have an outstanding safety record, especially when compared to other modes of transportation: According to the National Transportation Safety Board, in 2008, more than 42,000 transportation fatalities occurred on the highways, while aviation, boating and railroads accounted for another 2,000 fatalities. In contrast, there were only 12 fatalities associated with natural gas pipelines.

The largest single cause of pipeline accidents is excavator caused damages. Over 50% of the 500 damages to ENSTAR’s pipelines last year were done by excavators that failed to obtain locates. Call before you dig, it’s free and it’s the law. Calling for locates is now as simple as dialing 811. Dialing 811 anywhere in the United States connects you with the Locate Call Center for that area. In Alaska, dialing 811 connects you with Alaska Digline Inc. Alaska Digline Inc. will take your excavation information and notify all affected utilities. Utilities have two business days to mark their utilities after receiving your call.

Pressure Classification

Natural gas is a potentially dangerous, compressible gas. Gas pipelines with the highest pressure contain the highest stored potential energy and present the greatest risk. Caution is always warranted when working around natural gas facilities. Extreme caution must be exercised whenever transmission pipelines are encountered. Contact ENSTAR Engineering Dept., (907) 264-3740 for specific instructions before working within 10 feet of any transmission pipeline.

Pressure Classification

Pressure Rating Range

Pipeline Material

Transmission Pressure

Greater than 60 psig


Distribution Pressure

60 psig or less

Polyethylene, Steel, Copper

Recognizing ENSTAR‘s Pipelines

ENSTAR transmission pipelines are generally marked above ground with pipeline markers similar to the one shown. Transmission pipelines are located in the vicinity of the pipeline markers. Transmission pipelines are steel and range in size from 4” to 20” in diameter. They are typically coated with a protective coating. There is no single color but yellow and black are the predominant color while some are green or brown.

Distribution pipelines are steel, copper or polyethylene. These pipelines range in size from ½” diameter to 12” in diameter. Gas “Mains” are typically found in street right-of-ways or utility easements and supply the natural gas to an entire street or subdivision. They are typically steel or polyethylene and range in size from 2” to 12” in diameter.

Natural gas “service lines” are connected to the gas main and generally serve a single building or small group of buildings on private property. They are typically ½” to 1” in diameter. Service lines can be rigid steel, steel tubing, copper or polyethylene. Gas mains and service lines are generally steel or yellow in color.

Excavation Requirements for Natural Gas Pipelines

  1. Line Locating is a Free Service: To request a locate, dial 811 the new Nationally recognized One-Call number and you will be connected to Alaska Digline Inc. Call at least two but not more than 15 working days before the date scheduled for beginning the excavation. Hand digging is advised when excavating within 2 feet of a marked facility. After ENSTAR has field marked with yellow paint, or flagged the location of an underground facility, the excavator is responsible for maintaining the markings. Failure to call is a violation of state statutes and could result in fines well in excess of the cost of the damage.

  2. Support for Steel Line Crossings: If an excavation below a steel gas pipeline leaves the pipeline unsupported for a distance of more than 20 feet, the excavator must provide additional support for the pipeline. Support must be provided in a way as to not damage the pipe or its coating during construction, backfill placement, and compaction. Generally, a support spacing of 5 feet or less will provide the needed bracing. ENSTAR Engineering must approve all excavations crossing steel pipelines above 4-inch diameter. If support is required, ENSTAR engineering written approval is required prior to beginning construction. Call ENSTAR Engineering (907) 264-3740 for further information. Extra care must be taken when geotextile fabric and/or rigid insulation are used. In addition to continuous support under the pipeline, compacted fill material shall be placed between the geotextile fabric/rigid insulation and the pipeline. Care shall be taken to insure stability for the ENSTAR facility. Failure to properly protect ENSTAR’s facilities could result in future damage if differential settlement occurs.

  3. Support for Polyethylene Line Crossings: If an excavation is below a polyethylene gas pipeline the excavator must continuously support such pipeline during construction, backfill placement, and compaction. Geotextile fabric and/or rigid insulation shall be sufficiently separated from the polyethylene gas pipeline to prevent undue stress during the compaction/settlement process. (see item 8 clearance)

  4. Excavation Parallel to Pipeline: When parallel excavations are expected to expose or undermine sections of pipeline, the excavator must notify ENSTAR engineering in advance. Care must be taken not to damage the pipeline, or to induce stresses due to differential settlement following construction. Long parallel excavations exposing pipelines can be very dangerous if not properly performed and shall not be attempted without prior approval by ENSTAR. Contact ENSTAR Engineering at 264-3740 for additional information.

  5. Blasting: All blasting that is to be done within 500’ of any Company Facility, shall be reviewed by an ENSTAR engineer, with the person performing the blasting and appropriate measures, (i.e. require minimum distance from facilities, minimize blasting charge intensity, etc.) shall be taken to protect the integrity of the Company’s Facilities. A leak survey shall be performed after any blasting activity, which is within 500’ of any Company Facility. The leak survey zone shall include all Company Facilities within 500’ radius of the blasting.

  6. Trenchless Excavation (Vertical or Horizontal): Whenever a trenchless excavation (horizontal or vertical) is performed within 5 feet of a distribution pressure pipeline and 10 feet of a transmission pressure pipeline, the gas pipeline must be exposed to visually determine the exact location. If the trenchless excavation is expected to cross the pipeline within the aforementioned distances, the pipeline in question shall be fully exposed to a minimum of 1 foot beneath the pipeline prior to the expected crossing to ensure that the pipeline is not unduly damaged due to ground movement in the immediate vicinity of the pipeline. When performing a trenchless excavation parallel to a gas pipeline, the gas pipeline must be exposed at intervals of 25 feet or less to visually determine the pipeline’s exact location. Trenchless excavation is defined as drilling, directional drilling, boring, pile installation etc.

  7. Clearance: Natural Gas pipelines require a 12 inch minimum separation from other underground structures not associated with ENSTAR’s pipeline system. Additional clearance from other underground structures may be required to allow proper maintenance and reduce the possibility of damage due to the proximity of other structures (49 CFR § 192.325.) This clearance requirement includes rigid insulation and geotextile fabrics. ENSTAR requires a 36-inch minimum separation from certain electrical facilities, including any grounded components i.e. ground rods, non-insulated conductors and associated structures.

  8. Pipeline Cover: ENSTAR pipelines in public rights-of-way are generally installed with 36 inches to 48 inches of cover, and in private rights-of-way with 12 inches to 36 inches of cover. Projects that decrease cover or increase cover in excess of 60 inches must receive prior approval from ENSTAR Engineering Department (907) 264-3740. ENSTAR has limited ability to prevent the removal of cover over gas pipelines. Increasing pipeline cover more than 5 feet or decreasing pipeline cover to less than 3 feet may be considered a damage that may result in relocation of the gas pipeline at the expense of the Excavator. The depth of cover listed above cannot be assumed after installation. The excavator is responsible for any damage to ENSTAR pipelines regardless of the depth at which they are encountered.

  9. Inspection: All excavations in the immediate vicinity of ENSTAR Natural Gas facilities (including backfill, compaction, temporary support, and shoring), is subject to prior approval and inspection by ENSTAR personnel. Transmission pipeline inspections are provided whenever an excavator is working within ten feet of a transmission pipeline. If it has been determined that there was excavation either by hand or machinery within 5 ft. of ENSTAR Natural Gas Distribution mains or 10ft. from ENSTAR Natural Gas Transmission mains without either locates or standby (qualified ENSTAR personnel), ENSTAR Natural Gas reserves the right to excavate to determine if there has been any damage to ENSTAR Natural Gas facilities. If damage has occurred ENSTAR Natural Gas has the right to charge the excavator for repairs. 

Pipeline Components

Pipe Wall Protection

Dents, scrapes, gouges and scratches reduce pipeline wall thickness and affect the safety of the facility in two ways. First, the reduced wall thickness decreases the pressure at which the pipeline can safely operate. Second, the damage serves as a stress concentration that can cause a future brittle failure of the pipeline. An ENSTAR representative must inspect each dent, scrape, gouge or scratch, no matter how small, before it is reburied.

Corrosion Protection

ENSTAR’s steel pipelines are protected from corrosion by a dielectric coating and an impressed current or galvanic anode cathodic protection system. Direct contact with metallic objects (a short) or removal of the protective coating can compromise this system. Contact the ENSTAR Engineering Department (907) 264-3740, whenever coating damage or a short is encountered. An ENSTAR representative must inspect each short or section of damaged coating  before it is reburied.

Locate Wire Protection

ENSTAR’s polyethylene pipelines are installed with a parallel copper wire, which is used to locate the pipeline. If the locate wire or wire coating is damaged, ENSTAR’s ability to properly locate the pipeline may be severely compromised. Electrical continuity must be maintained. An ENSTAR representative must inspect each possible locate wire damage before it is reburied.


Service Line Excess Flow Valves


Excess Flow Valve (EFV) is a safety device installed in a natural gas service line near the gas main that is designed to automatically shut off the flow of natural gas in the event that the service line is broken. Effective February 12, 2010, all gas companies nationwide are required to install an EFV in any newly installed service line that serves one single family dwelling. Starting this year, ENSTAR will be installing an EFV in all new service lines that meet this requirement. ENSTAR will not be installing EFVs on service lines that branch to multiple buildings, multi-family, commercial or industrial structures. ENSTAR will not be installing EFVs on the existing 100,000 service line currently in use.

What does this mean to you as an Excavator?

Should you dig into a natural gas service line that has an EFV, the gas will blow for a short duration and shut off automatically if the flow of gas is sufficient to close the EFV. Damages that do not sever the service line completely may not cause the EFV to close and the gas will continue to blow. Regardless, you must report all damages to ENSTAR immediately. EFVs are designed to allow a small amount of “bleed-by” so they can be reset without excavating the gas main. Backfilling a damaged service line with gas bleeding underground is extremely dangerous and could fuel an explosion if it is not repaired timely. Do not assume a damaged service is dead or abandoned if it is not blowing gas. The EFV may have shut down the flow of gas. Report all damages immediately by calling 277-5551.
Please remember that the vast majority of ENSTAR service lines WILL NOT have an EFV. Should you damage a service line without an EFV, gas will blow at full line pressure until ENSTAR can arrive to shut it off. Your best protection against damaging underground utilities is to call 811 for locates and hand dig within 2’ of locate marks.

What to do if you damage a gas line or Smell Gas

If you damage a pipeline facility, call ENSTAR’s 24-hour dispatch number at 277-5551. Call ENSTAR any time a gas line is broken, scraped, pulled, cut or otherwise damaged. If the damage results in a release of natural gas and there is a danger to life or property, you should call the local Fire Department or 911. Eliminate all ignition sources and evacuate the area of the damage. Wait for an ENSTAR employee to shut off the flow of gas and make repairs.

Gas lines that have been pulled, stretched, kinked or bent could be damaged underground away from where the line is connected. If you pull or stretch gas lines call ENSTAR at 277-5551 and an ENSTAR Representative will investigate for possible underground leakage.

Qualified Personnel Requirements

Only qualified individuals meeting all applicable requirements may perform work on ENSTAR Natural Gas Company facilities. At a minimum, such individuals must comply with applicable federal, state and local regulation, statutes, and ordinances.