Page 76 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

Assessing third-party damage potential 3/55

Signscompany name
emergency pnone

x-x- x-x-

Painted fenceposts
x-x-

Figure 3.7 ROW condition.

excavation works. This is estimated to be around 775 unreported Land movements-landslides, subsidence. bank erosion,
excavations per year on their 10,400-km system [ll]. While creek or riverbank instability, etc.
unreported excavation does not automatically translate into Construction activi+both nearby and likely to move
pipeline damage, obviously the potential exists for some of those toward the ROW
775 excavations to contact the pipeline. These numbers represent Encroachments-utbuildings, landscaping changes, gar-
a U.K. situation that has no doubt changed with the increasing dens, etc., may warrant additional investigation
use of one-call systems, but some countries do not have formal Unauthorized activities on ROW-off-road vehicles, motor-
notification systems and rely on patrols to be the primary means cycles, snowmobiles, etc.
of identifying third-party activity near their pipelines. Missing markershigns
From a reactive standpoint, the patrol is also intended to Evidence of vehicular intrusions onto ROW-highway acci-
detect evidence of a leak such as vapor clouds, unusual dead dent, train derailment, etc.
vegetation, bubbles from submerged pipelines, etc. As such, it Plantings of trees, gardens
is a proven leak detection method (see Chapter 7 on the leak Third-party changes to slope or drainage.
impact factor).
From a proactive standpoint, the patrol also should detect Slope issues can be an important but often overlooked
impending threats to the pipeline. Such threats take the form of aspect of pipeline stability, detectable to some extent by patrol.
excavating equipment operating nearby, new construction of Slope alterations near, but outside, the right-of way by third par-
buildings or roads, or any other activities that could cause a ties should be monitored. Construction activities near or in the
pipeline to be struck, exposed, or otherwise damaged. Note that pipeline right-of-way may produce slopes that are not stable and
some activities are only indirect indications of threats. New could put the pipeline at risk. These activities include excavation
building construction several hundred yards from the pipeline for road or railway cuts, removal of material from the toe of a
will not pose a threat in itself, but the experienced observer will slope, or adding significant material to the crest of a slope. The
investigate where supporting utilities are to be directed. Con- ability to detect potentially damaging land movements is also a
struction ofthese utilities at a later time may create the real threat. risk mitigation measure discussed in Chapter 5.
The patrol should also seek evidence of activity that has One measure of patrol effectiveness would be data showing
already passed over the line or land movements. Such evidence a number of situations that were missed by the patrollers and
is usually present for several days after the activity and may or accompanying observers when the opportunity was there.
warrant inspection of the pipeline. Indirect measures include observer presence, patroller/
Training of observers and possibly the use of checklists are observer training, and analysis of the “detection opportunity.”
important aspects of patrol effectiveness. Reportable observa- This opportunity analysis would look at altitude and speed of
tions should include the following: aerial patrol an4 for ground patrol, perhaps the line of sight