study. At a section between
Highway 138 and the Lone
Pine Canyon, the lines
experienced slow foundation
movement or shifting at a '7 k 
region were a local bowl or I I' 
depression exists. The V; , 
cause was determined to be a
high water table fed by
surface waters collected in
I s 
the bowl that allowed the
tower foundations to slowly
respond to the tension
imposed by the lines
themselves. The solution
was found to be to cover the
ground with a concrete
mixture so that surface
waters would could not seep
into the water table at that
location. The towers now
appear to be stable. On
several other occasions,
local brush/forest fires
have heated the copper
conductors to the extent
that they partially annealed
and sagged. This problem
was resolved by retensioning
the line in those regions.
It is of importance because
it indicates the problems Figure 19 Power Tower At A Ravine Edge
that earthquake-induced
fires could have on this In The San Andreas Fault Rift Zone
lifeline system.
The LADWP power lines cross the San Andreas fault zone in Lone Pine
Canyon very close to where the petroleum products and a 36-inch
natural gas transmission line cross the fault trace (see Figures 18
and 19). The expected 12 meter fault displacement causes a damage
state 7 to all the lifeline components in this region, with a
probability of 100%. The collocation scenario assumes that the
resulting petroleum products spill (several miles of those
pipelines could drain from the rupture, depending on how many other
ruptures are assumed since the petroleum products pipelines run
parallel to the fault trace for several miles) causes a 30-day
delay in the repair activities while the resulting environmental
and fire hazards are evaluated and mitigated. The general
congestion in the area and the need to coordinate the use of heavy
equipment so that its use will not adversely impact the other
lifelines is assumed to add another seven days to the power line
repair times. Because of the high probability of damage at this
location, the probable restoration time increases by 37 days. This
accounts for about 75% of the collocation-induced delays in the
restoration of service to the LADWP power lines.
The other significant collocation region for the LADWP power lines 
is also at Blue Cut. The power lines cross the eastern edge of a
landslide zone, and at the toe of the zone at a lower elevation a 
36-inch natural gas pipeline is sited next to and in the right-of-
way of a rail line. The probability of a slide in this region is
70%, it produces a power line damage state of 5 (heavy damage).
The collocation scenario includes a seven day period while the gas 
line is prepared and tested for leaks, and a increase in damage
state to level 6 because of potential natural gas pipeline failure 
impacts. That scenario increased the repair time from 49 to 66 
days and the net impact on the change in restoration time was about
12 days.
There are three 500 kV circuits on SCE's Lugo -Mira Loma system. 
They were installed in the early 1960s for about 300 kV service and
Line 3 was added in
upgraded to 500 kV service in the early 1970s. 
1983.
Line 1 is to the west, line 2 is in the center, and line 3 is the
eastern line. Line 1 is routed south by southwest from the Lugo
substation. Lines 2 & 3 leave Lugo station on a single tower 
system for about 1.5 miles, then they divide into two separate
tower systems. The power lines cross the railroad lines a short
distance before they cross Highway 138. From there they head
generally south until they cross I-15. In this high desert region
the only earthquake load comes from shaking characterized by MMI = 
VII. At that intensity there is no appreciable damage to the
towers or the lines, and no collocation impacts were hypothesized.
At the I-15 crossing, lines 1 & 2 cross at the northern boundary of 
a local liquefaction zone. Because their power towers are located 
on local hill tops in this region, it is assumed that there are no
impacts due to the liquefaction or due to collocation. However,
they cross near a concrete culvert that crosses under the highway.
At the culvert (see Figure 12) location there is also a metal crib
wall (see Figure 13) that provides support to the road bed, the 
fiber optic cables cross at the same location, there are two
railroad bridges in the downstream path from the run off that
passes through the culvert, and there is a 36-inch natural gas line
which crosses I-15 in the same area. In addition, the crossing is
in an area of high water table and of surface water, indicating a 
potential liquefaction zone. Although the power towers and lines
are not expected to experience damage at this location, they will
cause some delays in responding to damage on the other lifelines
and other equipment
because of the need to work with large cranes 
that could get close enough to the power lines to cause the need
for caution to avoid potentials for electrocutions, etc... Line 3
crosses I-15 further south and is not impacted by the crowded
conditions described above.
After crossing I-15, lines 1 & 2 are routed as parallel lines.
Where they cross the San Andreas fault they will experience damage
state 7 due to the 12 meter displacement expected at the fault
trace. The two lines pose a collocation potential that is assumed
to increase their repair time by 15 days. This increases their
probable restoration time by 15 days because of the high
probability that the large fault displacement will occur. After
this, the lines again separate, with line 1 heading south, and line
2 heading southeast until it joins with line 3 at Blue Cut.
As line 1 heads south it enters a liquefaction zone that is north
and abuts against a landslide zone. Within the liquefaction zone
it crosses over the two petroleum product pipelines, the fiber
optic conduits, and Cajon Blvd. extension. Near the boundary
between the liquefaction and landslide zones it crosses over a 36inch 
natural gas pipeline that is itself next to and in the right-
of-way of a railroad line. The liquefaction zone results in a 50%
probability of damage state 7 occurring to the power towers. The
collocation scenario is a 20 day delay due to the general
congestion in the region, which results in a probable delay in
restoration of 4 days. There are no other significant collocation
regions for line 1 further south along its route.
After they join together, lines 2 & 3 head in a south by southeast-
direction. They cross the Cajon Blvd. extension at the northern
boundary of a local liquefaction zone and head up the steep slopes
to the higher elevations of the San Gabriel Mountains. Just above
the Cajon Pass floor as they rise into the mountains they enter a
landslide zone. Figure 17 shows that in the past they have
experienced slides that have required extensive repair. At the toe
of the slide a 36-inch natural gas pipeline is located next to and
in the right-of-way of a railroad bed. The landslide causes a
damage state 5 (with a probability of 45%). It is assumed that the
congestion and the need to shut down the power line when the gas
pipeline is to be tested for leaks will add 40 days to the repair
of the power towers. This makes their probable restoration time
increase by nine days at this location.
The typical collocation damage scenario is that other lifelines
have a minor physical impact on power lines because the power lines
are above or removed from the zone of influence of the other
lifelines. However, when fuel-based lifelines are involved, they
can cause important delays in the power line restoration. This is
to assure that the power lines do not become a source of ignition
for the fuel. Also, when the other lifelines are directly under
the power lines, the expected use of temporary support towers may
not be acceptable because of the increased risk of electrocution
when other large repair equipment is operated near a temporary
tower. As was the case for the communication lifelines, ground
movement was the principal cause of electrical transmission
lifeline damage. 
One hundred and four collocations involving the electric power 
lifelines were analyzed. The overall estimate of the impact of 
collocation on the electric power lifelines in the Cajon Pass was: 
Increase in Probable Increase in Probable 
Time to Restore Time to Restore 
Lifeline Service. days Service. % 
Los Angeles Dept. 
of Water & Power 
49 28 
Southern California 19 10 
Edison Co. Line #1 
Southern California 28 13 
Edison Co. Line #2&3 
Fuel Pipeline Lifelines 
Figure 20 shows the fuel pipeline lifeline routes in the study 
area. The location of the photographs presented in this section of 
the report are also shown on the figure. The lifelines include one 
8-and one 16-inch petroleum products pipelines, three 36-and one 
16-inch natural gas pipelines, and the associated valves for each 
line. Modern 
buried 
pipelines of 
the type 
installed at 
Cajon Pass 
are very 
resistant to 
shaking
damage.
Thus, the 
earthquake
conditions of 
most interest 
for the 
pipelines are 
the 
conditions 
where ground 
movement is 
expected.
However, when 
they are 
buried next 
to or under Figure 21 Typical Long Open Span On The 36-Inch 
another Natural Gas Pipeline 
Figure 20, FUEL PIPELINE LIFELINE ROUTES 
SCALE 
LargerScale 
figure
EXPLANATION Located at 
End of Document
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a PAID SUBWAY 
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they are with
the
railroads),
there is an
additional
concern that
heavy
equipment
used to
remove debris
or otherwise
restore the
railroad
lifeline
could lead to
pipe wall
damage of the
nearby buried
fuel
pipeline.
Because they Figure 22 Two Natural Gas Pipelines Near Highway 138,
are buried, One Buried, One Exposed
there are no
convenient
features that can be shown with photographs. However, there are 18
locations along the route of the western most 36-inch natural gas
pipeline that are exposed spans which range from 10 to 138 feet in
length. Figure 21 shows one of the longer spans across a dry creek
bed north of Highway 138 and east of I-15. Figure 22 shows a
location about 40 feet from the recently realigned Highway 138. At
that location two 36-inch natural gas pipelines are routed parallel
to each other. The line on the left is exposed, the one on the
right is buried and marked with the surface sign. In general, open
spans are estimated to increase the potential shaking damage state
by up to 1 level, compared to a buried pipeline damage state
condition.
When the pipelines cross under railroads, roadbeds, and sometimes
power line rights-of-way, many of the right-of-way owners required
the pipeline to be cased inside a larger pipe in the belief that
this adds safety and/or it reduces the lifeline interactions if
damage on one lifeline should occur (there is a current technical
question whether the casing increases or reduces the overall safety
of the crossing). Figure 23 shows a location where a 36-inch
natural gas transmission line crosses under two different rail
beds. One railroad requires the use of the extra casing, the other
does not. If the use of a casing increases the safety of the
crossing, the close proximity of the railroads means that the extra
benefit is lost. If the use of a casing decreases the safety of
the crossing, then the railroad expecting extra safety has not
77
achieved it because of the close proximity in this situation. 
Two of the most critical collocations involving fuel pipelines were 
shown in Figures 17 and 18. In Figure 17 the pipeline and the 
railroads are located directly below a landslide prone area that 
includes electrical transmission towers. Figure 18 shows that both 
types of fuel pipelines and high voltage electrical transmission 
systems all cross the San Andreas fault rift zone at approximately 
the same location. The results of these conditions are discussed 
below. 
The western most 36-inch natural gas pipeline from valve station 14 
(near the Cajon railroad summit east of the I-lS/Highway 138 
interchange) south to the end of the study area was installed in 
1960. The eastern most 36-inch natural gas pipeline was installed 
in 1966. They operate at a mean operating pressure of 845 psig. 
The 16-inch distribution supply line branches off of those lines at 
Valve 15 (south and west of 
the 1-15/1-215 interchange) 
and provides service to San 
Bernardino. It operates at 
a mean operating pressure of 
350 psig. The line from the 
north of the study area 
(along Baldy Mesa Road) to 
valve station 14 was 
installed in 1976. It 
operates at a mean operating 
pressure of 936 psig. All 
of the lines were arc welded 
and constructed from high 
grade steel pipe. They
deliver 0.6-1.0 billion 
cubic feet of natural gas 
per day. 
The 8-inch petroleum 
products pipeline was 
installed in 1960 and the 
14-inch line was installed 
in 1969. In 1980, several 
miles of the 8-inch line 
were abandoned and a new 
line was routed from the 
west side of Cajon Creek to 
join the 14-inch line on the 
east side. On the east side 
of Cajon Creek they are 
routed along the Cajon Blvd. 
extension. The lines 
transport a number of ?igure23 Natural Gas Pipeline 
refined products, the Crossing Under Railroad Beds 
transport a number of refined products, the principal ones being
gasoline and jet fuel. They are made of high grade carbon steel.
They operate at 1060-1690 psig. The lines pump about 30,000
barrels of fuel per day.
Most of the pipeline highway or railroad bed crossings are cased
crossings. However, none of the Southern Pacific crossings are
cased, and a few of the I-15 and Highway 138 crossings are uncased.
That occurred because the Southern Pacific did not require casing
when they authorized the right-of-way crossing, and when I-15
replaced Highway 66 and when Highway 138 was recently realigned (in
1990-1991) they did not follow all of the old routes. At new
crossings the pipeline was already installed, and new casings were
not required to be retrofit.
In the regions of MMI = VII or less, the shaking damage state for a 
buried gas or petroleum products transmission line is 1, and no
collocation damage is estimated except for unusual conditions to be
described below.
Following the pipelines from the center of the northern part of the
study area and heading south, the first location for significant
damage occurs at the crossing of the San Andreas fault. Here the
12 meter fault displacement is assumed to rupture the lines. The
location includes the 36-inch natural gas pipeline and the two
petroleum products pipelines (all of which rupture) and the
Victorville-Century 287.5 kV lines 1 and 2. The damage scenario
includes assuming that an explosion/fire occurs in addition to the 
discharge of petroleum products. The need to mitigate the impact
of the fire and adverse environmental conditions and the delays 
caused by the general congestion in the area results in an assumed 
37 day delay before restoration work can begin. Because of the
high probability (100%) of the damage state, the incremental
increase in the lifeline restoration time is also 37 days.
At Blue Cut the natural gas pipeline is next to the railroad bed
and at the toe of a landslide area. High voltage power lines are
located above the gas line in the slide area. A damage state 4 is
predicted for the pipeline. The heavy equipment used to clear the
railroad bed is assumed to increase the damage state to level 5.
This increases the pipeline repair time by 18 days, and the debris
clean up adds another 20 day delay. The general congestion adds a 
7 day delay. This results in a change in the most probable 
restoration time of 12 days. Further south the pipeline follows
the railroad bed along the west edge of Cajon Creek. About 4 miles
further south, the pipeline and railroad are again at the toe of a 
landslide region. In this case only the 18 day increase in repair
time and the 20 day debris removal delay are assumed. This results
in an 8 day increase in the probable restoration time for that 
pipeline, for a total increase in time of 20 days.
Moving from the north to the south, the eastern most natural gas 
pipeline first experiences a potential collocation damage condition
where it crosses I-15 in the region where the fiber optic conduits
cross under I-15 in a concrete culvert and the electric power lines
cross over the highway. This is a region of potential
liquefaction. The damage state is 7 but the probability of damage
is only 20% for the pipeline (but 40% for the lifelines that are
right in the local creek bed). The pipeline is somewhat removed
from the other lifelines, but there are railroad bridges also in
the general area. It is assumed that the other lifeline repairs
will be based on the requirement that long lengths of the natural
gas pipeline will need to be exposed and examined to assure that a
leak/explosion potential does not exist while they work on the
other lifelines. This leads to a 20 day delay in starting the
pipeline repair, resulting in a probable restoration delay of 8
days. About 3.2 miles further south the pipeline passes through
another landslide zone near where it crosses I-15, leading to a
probable increase in the restoration time of 16 days.
Across Cajon Creek from where the western pipeline was exposed to a
potential landslide, the eastern natural gas pipeline crosses
perpendicular to the two petroleum product pipelines and the fiber
optic cables. This is a potential liquefaction zone that results
in a pipeline damage state of 7 with a probability of 20%. There
is a 30 day delay while the petroleum product spill is cleaned up
and another 7 day delay for general congestion resolution
questions. This results in an incremental change in the probable
restoration time of 2 day.
Just south of the I-15/I-215 interchange the 16-inch natural gas
pipeline crosses a local liquefaction zone. It is collocated with
the two petroleum products pipelines, the railroads, and two of the
fiber optic cables. The liquefaction results in a damage state 7
with a probability of 40%. The collocation damage scenario assumes
a 30 day delay to clean up the petroleum product spills, and
another 20 days to account for the congestion and delays
experienced because of the repair to the nearby bridges. The net
increase in restoration time is 8 days.
The two petroleum products pipelines enter the study area from the
south in the Cajon Creek Wash. The 14-inch lines is collocated
along the railroad right-of-way, the 8-inch is on the western side
of the wash. Just south of the I-15/I-215 interchange, the 14-inch
pipeline enters a local liquefaction zone, along with the 16-inch
natural gas pipeline, the railroads, and two fiber optic cables.
Damage state 7 (40% probability) occurs in this region. There is a
20 day delay due to the general level of congestion, and because
the 14-inch pipeline is collocated with the railroad, there will be
a requirement to expose and inspect the pipeline before it can be
put back into service. This will add another 40 days of delay.
This results in a 10 day increase in the probable time to restore
service. About 6 miles further north, both pipelines enter another
liquefaction region, along with a 36-inch natural gas pipeline and