| (a) This section applies to each operator of a gas
distribution system that is subject to the requirements of 49 CFR
Part 192.
(b) Each operator shall have either a prescriptive
or a risk-based program for leak surveys for its pipeline systems
that complies with the requirements of this section. Such program
shall require a designation on a system by system basis or by segments
within each system whether the operator has chosen to use the risk
based leak survey program that complies with the requirements of subsections
(c) through (f) of this section or the prescriptive leak survey program
that complies with the requirements of subsection (g) of this section.
(c) Each operator shall create a risk model on which
to base its leak survey program to identify those systems or segments
within systems that pose the greatest hazard and thus will be inspected
for leaks more frequently. The risk model shall identify risk factors
and determine the degree of hazard associated with those risk factors.
The operator shall establish the leak survey frequency based on the
degree of hazard for each system or segment within a system.
(d) Each operator shall periodically re-evaluate each
pipeline system or system segment and update its leak survey inspection
program to address any changes that may be identified through the
monitoring of the pipeline system in accordance with the requirements
imposed by 49 CFR §192.613 (relating to Continuing Surveillance).
Each operator shall not less than every three years at intervals not
exceeding 39 months review its leak survey inspection program. Each
operator shall review its leak survey inspection program within 30
days in the following circumstances:
(1) to add a new system or segment being put into operation;
or
(2) if, for any system or segment, there has been a
ten percent increase in the number of leaks being upgraded or a ten
percent increase in the number of unrepaired leaks.
(e) Based on the particular circumstances and conditions,
an increased frequency beyond that required by 49 CFR §192.723(b)(1)
and (2), may be warranted. Surveys should be conducted more frequently
in those areas with the greatest potential for leakage and where leakage
could be expected to create a hazard. Each operator should consider
the following factors in establishing an increased frequency of leakage
surveys:
(1) pipe location, which means proximity to buildings
or other structures and the type and use of the buildings and proximity
to areas of concentrations of people;
(2) composition and nature of the piping system, which
means the age of the pipe, materials, type of facilities, operating
pressures, leak history records, and other studies;
(3) the corrosion history of the pipeline, which means
known areas of significant corrosion or areas where corrosive environments
are known to exist, cased crossings of roads, highways, railroads,
or other similar locations where there is susceptibility to unique
corrosive conditions;
(4) environmental factors that affect gas migration,
which means conditions that could increase the potential for leakage
or cause leaking gas to migrate to an area where it could create a
hazard, such as extreme weather conditions or events (significant
amounts or extended periods of rainfall, extended periods of drought,
unusual or prolonged freezing weather, hurricanes, etc.), particular
soil conditions, unstable soil or areas subject to earth movement,
subsidence, or extensive growth of tree roots around pipeline facilities
that can exert substantial longitudinal force on the pipe and nearby
joints; and
(5) any other condition known to the operator that
has significant potential to initiate a leak or to permit leaking
gas to migrate to an area where it could result in a hazard, which
could include construction activity near the pipeline, wall-to-wall
pavement, trenchless excavation activities (e.g., boring), blasting,
large earth-moving equipment, heavy traffic, increase in operating
pressure, and other similar activities or conditions.
(f) The assignment of inspection priorities is based
on the degree of hazard associated with the risk factors assigned
to the pipeline system or segments within a system. The determination
of leak survey frequency is determined by classifying each pipeline
segment based on its degree of hazard associated with each risk factor.
Each operator shall establish its own risk ranking for pipeline segments
to determine the frequency of leakage surveys. Based on a ranking
from high to low, each operator shall schedule leak inspections for
a given pipeline system or segment within a system on a time interval
necessary to address the risks. The time interval may range from quarterly
to every five years.
(g) Operators electing to use a prescriptive leak survey
program shall conduct leak surveys no less frequently than:
(1) Once each calendar year at intervals not exceeding
15 months for all systems within a business district;
(2) every five calendar years at intervals not exceeding
63 months for non-business district polyethylene systems or segments
within a system;
(3) every three calendar years at intervals not exceeding
39 months for all other non-business district cathodically protected
steel systems or segments within a system; and
(4) every two calendar years at intervals not exceeding
27 months for all other non-business district systems or segments
within a system.
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