Document ID: PHMSA-2016-0065-0001
Agency: phmsa
Document Type: Notice
Title: Pipeline Safety: High Consequence Area Identification Methods for Gas Transmission Pipelines
Posted Date: 2016-12-13T05:00Z

[Federal Register Volume 81, Number 239 (Tuesday, December 13, 2016)]
[Notices]
[Pages 90062-90064]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-29880]

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DEPARTMENT OF TRANSPORTATION

Pipeline and Hazardous Materials Safety Administration

[Docket No. PHMSA-2016-0065]

Pipeline Safety: High Consequence Area Identification Methods for 
Gas Transmission Pipelines

AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA); 
DOT.

ACTION: Notice; Issuance of Advisory Bulletin.

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SUMMARY: PHMSA is issuing this advisory bulletin to remind gas 
transmission pipeline operators of certain previously issued guidance 
and provide operators with additional guidance for the identification 
of High Consequence Areas (HCAs) along pipeline right-of-ways. This 
advisory bulletin provides suggestions for accurately mapping and 
integrating HCA data, documenting how mapping systems are used, 
periodically verifying and updating their mapping systems, utilizing 
buffer zones (tolerances) to provide additional protection around the 
calculated potential impact radius (PIR) along their pipelines, and 
ensuring the accuracy of class locations. The bulletin emphasizes that 
HCA identification relies on pipeline-specific information regarding 
the location, size, and operating characteristics of the line, as well 
as the identification of structures, specified sites, and their 
intended usage along the pipeline right-of-way.

FOR FURTHER INFORMATION CONTACT: Allan Beshore by phone at 405-834-8344 
or email at allan.beshore@dot.gov. All materials in this docket may be 
accessed electronically at http://www.regulations.gov. Information 
about PHMSA may be found at http://www.phmsa.dot.gov.

SUPPLEMENTARY INFORMATION: 

I. Background

    A key component of PHMSA's pipeline safety regulations is its 
integrity management (IM) program. For gas transmission pipelines, this 
program is outlined in Subpart O of 49 CFR part 192 and is based on the 
concept that pipeline operators need to identify those segments of 
their pipeline systems that pose the greatest risk to human life, 
property, and the environment, and to take extra precautions to ensure 
their safety. These higher-risk areas are known as ``HCAs.'' Each 
operator is required to survey its entire pipeline system to identify 
all pipeline segments

[[Page 90063]]

that could affect HCAs. Since the greatest risk posed by gas 
transmission pipelines is the risk of fire and explosion resulting from 
pipeline leaks and ruptures, gas HCAs consist of highly populated areas 
and ``identified sites'' where people regularly gather or live.
    An operator's first step in developing a robust IM program is to 
properly identify and map all HCAs and perform periodic updates to the 
evaluation process to maintain accurate and current information. 
Subpart O of part 192 allows operators flexibility in making 
determinations to identify HCAs by defining two different 
identification methods, generally referred to as Method 1 or Method 2.
    Both methods require the operator to determine ``identified sites'' 
and calculate a PIR, using a formula to calculate the radius of a 
circle within which the potential failure of a pipeline could have 
significant impact on people or property. While Method 1 includes all 
pipe segments within Class 3 and Class 4 locations\1\ and ``identified 
areas within a PIR in Class 1 and 2 locations,'' Method 2 includes 
``identified sites'' \2\ within a PIR only, regardless of the class 
location, or the combination of ``identified sites'' with 20 or more 
buildings intended for human occupancy.
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    \1\ Under 49 CFR 192.5, all transmission pipelines fall into one 
of four ``class locations.'' Class 1 locations are offshore areas 
and all segments (``class location units'') one mile in length that 
contain 10 or fewer buildings intended for human occupancy Class 2 
locations are units with more than 10, but fewer than 46, such 
buildings. Class 3 locations are units with 46 or more buildings or 
an area where the pipeline lies within 100 yards of either a 
building or a small, well-defined outside area (such as a playground 
or recreation area) that is occupied by 20 or more people on at 
least 5 days a week for 10 weeks in any 12-month period. Class 4 
locations are units where buildings with 4 or more stories are 
prevalent.
    \2\ ``Identified sites'' is a defined term under 49 CFR 192.903 
in PHMSA's IM regulations and refers generally to the type of 
specific areas included under the Class 3 location definition above, 
plus facilities occupied by persons who are confined, are of 
impaired mobility, or would be difficult to evacuate, including 
schools, prisons, nursing homes, etc.
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    A review of PHMSA and state data from ``first-round'' IM 
inspections indicates a large percentage of intrastate and small 
operators have been inconsistent in determining HCAs using ``identified 
sites,'' and operators that initially used Method 1 to identify HCAs 
have since transitioned to Method 2.
    On July 17, 2003, (68 FR 42458) PHMSA published an advisory 
bulletin titled ``Identified Sites as Part of High Consequence Areas 
for Gas Integrity Management Programs'' to provide guidance to gas 
transmission operators on the steps PHMSA expected them to take to 
determine ``identified sites'' along their pipelines. PHMSA intended 
the guidance in the advisory bulletin to support operators in 
identifying these sites for planning their IM programs and determined 
that certain measures, if properly applied, would satisfy the intent of 
the regulation.
    On December 15, 2003, (68 FR 69778) PHMSA published a final rule 
titled: ``Pipeline Integrity Management in High Consequence Areas (Gas 
Transmission Pipelines)'' that provided requirements for the 
identification of HCAs and further explanation of how best to conduct 
the identification process.
    In the preamble of the rule, PHMSA provided the basis for defining 
an identified site as follows:
    Define an identified site as any of the following within a 
Potential Impact Circle:
    1. A facility housing persons of limited mobility that is known to 
public safety officials, emergency response officials, or local 
emergency planning committee, and which meets one of the following 
three criteria: (a) Is visibly marked, (b) is licensed or registered by 
a Federal, state, or local agency, or (c) is listed on a map maintained 
by or available from a Federal, State, or local agency, or
    2. An outdoor area where people congregate that is known to public 
safety officials, emergency response officials or local emergency 
planning committee and which is occupied by 20 or more people on at 
least 50 days per year, or
    3. A building occupied by 20 or more people 5 days per week, 10 
weeks in any 12-month period (the days and weeks need not be 
consecutive).
    To assist operators in meeting the requirements of the regulation, 
PHMSA introduced a ``buffer zone'' concept. This additional safety 
margin was intended to compensate for inaccuracies (e.g., incorrect 
pipeline center data or mapping errors) when implementing the 
regulation and determining the PIR. As defined in Sec.  192.903, a PIR 
is the radius of the potential impact circle (PIC), measured in feet 
surrounding the point of failure, within which the potential failure of 
a pipeline could have significant impact on people or property. Part 
192 provides the formula for determining a PIR that takes into account 
the Maximum Allowable Operating Pressure (MAOP) in the pipeline segment 
in pounds per square inch, the nominal diameter of the pipeline in 
inches, and a numeric factor, which varies for other gases depending 
upon their heat of combustion.\3\
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    \3\ Operators transporting gas other than natural gas must use 
section 3.2 of ASME/ANSI B31.8S (incorporated by reference, see 
Sec.  192.7) to calculate the impact radius formula. For flammable 
gases, additional information on factors may be found in TTO-13, 
Potential Impact Radius Formulae for Flammable Gases Other Than 
Natural Gas Subject to 49 CFR 192, June 2005, Table 7.1 which can be 
found in http://primis.phmsa.dot.gov/gasimp/docs/TTO13_PotentialImpactRadius_FinalReport_June2005.pdf).
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    Following the publication of the regulations and advisory bulletin, 
PHMSA inspections have revealed that operators may need further 
guidance regarding the identification of HCAs, as operators have been 
inconsistent in determining HCAs using ``identified sites.''
    Additionally, in CY 2015, the National Transportation Safety Board 
(NTSB) published SS-15-01, ``Safety Study: Integrity Management of Gas 
Transmission Pipelines in High Consequence Areas.'' The study was 
conducted in response to concerns about deficiencies in operators' IM 
programs that had been identified by the NTSB in three gas transmission 
pipeline accidents from the previous 5 years. Recommendation P-15-06, 
issued as a part of the study, recommended that PHMSA ``[a]ssess the 
limitations associated with the current process for identifying high 
consequence areas, and disseminate the results of [the] assessment to 
the pipeline industry, inspectors, and the public.'' PHMSA has noted 
that proper identification of an HCA and periodic verification relies 
on two key types of information: (1) Pipeline-specific information that 
includes the accurate location of the centerline of the pipeline, the 
nominal diameter of the pipeline, and the pipeline segment's MAOP; and 
(2) all the structures and their usage (including occupancy) located 
along the pipeline. PHMSA subject matter experts performed an 
assessment of the impact of these two issues on identifying HCAs using 
Methods 1 and 2 as defined in Sec.  192.903, by reviewing failure 
investigations, inspector experiences, and Gas IM inspection results 
and has documented these insights in this advisory bulletin. PHMSA will 
be including these insights in updated inspection materials, as 
appropriate.
    PHMSA is publishing this advisory bulletin to meet NTSB 
Recommendation P-15-06 by providing operators with additional guidance 
on how to improve the accuracy of their class location identification 
process, which may also lead to operators improving HCA identification.

[[Page 90064]]

II. Advisory Bulletin (ADB-2016-07)

    To: Owners and Operators of Natural Gas Pipelines.
    Subject: High Consequence Area Identification Methods.
    Advisory: PHMSA is issuing this advisory bulletin to inform owners 
and operators of gas transmission pipelines that PHMSA has developed 
guidance on the identification and periodic verification of HCAs, 
including the application of a buffer zone to the PIR, and information 
regarding the accuracy of class locations. PHMSA is recommending that 
operators review and consistently monitor class location and PIR data 
on an annual basis as part of their IM program. PHMSA anticipates this 
annual review will improve the accuracy of operator HCA determinations.
    A review of early PHMSA inspections has shown that many operators 
(28%) did not have procedures to adequately describe how to identify 
HCAs, using Method 1 or Method 2. To effectively use Method 2, 
operators should have a detailed and documented process in place to 
monitor the conditions surrounding their pipelines, including the 
existence of ``identified sites.'' Therefore, PHMSA is reminding 
operators of the existing guidance for making those determinations and 
is providing additional recommendations on how to improve the accuracy 
of HCA identification. Specifically:
     PHMSA expects that most large operators will use a 
geographic information system or similar mapping software for segment 
identification. Operators should be able to demonstrate the usability 
of their system and show a graphical overlay of HCAs with their 
pipeline system.
     An operator not using geographic information system or 
similar mapping software should describe or demonstrate how it 
performed its HCA segment identifications.
     For both geographic information system-based and non-
geographic information system-based HCA identification processes, the 
operator should address how it will deal with tolerances (or buffers) 
on top of the calculated PIR regarding the accuracy of measured 
distances to structures and the location of the pipeline centerline. 
PHMSA recognizes that global positioning system measurements and maps 
have some limitations in their accuracy; however, the rule applies to 
pipelines--and distances from those pipelines--as they actually exist 
in the field.
    PHMSA also reminds operators of the need to continually improve the 
accuracy of their pipeline data. As technology advances, pipeline 
operators have more access to tools that provide improved accuracy for 
determining class locations (including the determination of the 
centerline of the pipeline), the application of aerial photography, 
pipeline operating characteristics (diameter, grade, MAOP), population 
studies, and mapping software. It is important that operators 
continuously improve the accuracy of the data and conduct the required 
class location studies as required in Sec.  192.609, along with the 
confirmation or revision of MAOP in Sec.  192.611, as this affects the 
operation of their pipelines. Operators should include provisions in 
their continuing surveillance monitoring procedures (Sec.  192.613) to 
constantly monitor the surrounding conditions, report that information, 
and update their maps each calendar year. This is similar to the 
requirements for including newly identified areas for segments in HCAs 
(Sec.  192.905(c)) and for filing annual report information relating to 
the performance of IM plans (Sec.  191.17).
    Operators must use MAOP when calculating PIR, and accurate pipeline 
data is necessary to ensure that operators are correctly applying the 
MAOP value in the PIR calculation when determining whether areas 
qualify as HCAs. PHMSA also recommends that operators review their 
pipeline centerline and map data to account for any potential 
inaccuracies or data limitations and to add an appropriate buffer zone 
to the calculated PIR. This would establish a PIR that includes any 
areas that could potentially be excluded due to data limitations.
    A list of PHMSA-provided frequently asked questions on this subject 
can be found on the gas IM site at: https://primis.phmsa.dot.gov/gasimp/index.htm. Gas IM Frequently Asked Question Number 174 reminds 
operators that they should consider the uncertainties in the distances 
they measure or infer when evaluating PICs and consider geographic 
information system accuracy in locating HCAs:
    ``. . . Operators may use a combination of techniques in order to 
account for these inaccuracies. For instance, aerial photography may be 
used as an initial screen. Field measurements (such as pipeline 
locators along with chainage measurements or survey quality range 
finders) may be used to verify if structures near the edge of the PIC 
(i.e., within the range of mapping/geographic information system 
inaccuracies) are actually inside or outside the PIC. PHMSA will 
inspect each operator's approach to assure that the operator's process 
is adequate to identify all covered segments.''
    PHMSA recommends operators frequently and consistently review their 
data--including class location data--for potential inaccuracies or 
limitations, and add a buffer zone to the calculated PIR to help ensure 
proper HCA identification. The purpose and usage of buildings, open 
structures, and outside areas can shift over time, changing the number 
of ``identified sites'' in a PIR, and therefore, whether an area is an 
HCA. PHMSA believes that if operators review class location and PIR 
data on an annual basis as a part of their IM programs, the accuracy of 
HCA determinations will be greatly improved.

    Issued in Washington, DC, on December 8, 2016, under authority 
delegated in 49 CFR 1.97.
Alan K. Mayberry,
Acting Associate Administrator for Pipeline Safety.
[FR Doc. 2016-29880 Filed 12-12-16; 8:45 am]
 BILLING CODE 4910-60-P