Crews putting in a fiber optic line breached a gas main.
SF Gas fire
Several links on a page
Keith Cress
kcress -
SF Gas fire
Several links on a page
Keith Cress
kcress -
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Fiber optics install gone BAD.
- Thread starter itsmoked
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davidbeach
Electrical
Yes, locates are sometimes wrong, but excavation without locates is far too common. Or in the case of a similar type of event in Portland a few years ago the contractor got locates on the south side or the road and then excavated on the north side.
"Good old fashioned wooden Telephone Poles have their advantages."
"Not for gas lines."
When FO was installed (strung along telephone poles) in our neighborhood in 2014, they managed to avoid rupturing the large natural gas pipeline that runs through the area.
So I'd argue that good old fashioned wooden telephone poles have their advantages, especially for any nearby natural gas pipelines.
;-)!!
(Just kidding. I know what you meant.
"Not for gas lines."
When FO was installed (strung along telephone poles) in our neighborhood in 2014, they managed to avoid rupturing the large natural gas pipeline that runs through the area.
So I'd argue that good old fashioned wooden telephone poles have their advantages, especially for any nearby natural gas pipelines.
;-)!!
(Just kidding. I know what you meant.
![[bigsmile]](/data/assets/smilies/bigsmile.gif "[bigsmile] [bigsmile]")
As for the advantages of good ol' fashioned wooden telephone poles...
That's just one example. Hitting subsurface utilities is a universal hazard.
That's just one example. Hitting subsurface utilities is a universal hazard.
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Scotty; It's probably one of those things where there are big
signs everywhere and so it's assumed when a USA call is made all the yokels show up to mark the lack of sewer lines and water pipes and maybe no one shows up to mark the 36" transmission line because, well, DUH, there are already signs. Problem is they don't actually say where the line is other than 'near by'. Then if someone digs by hand carefully and finds the line safely they know where it is and proceed to drill their hole. Unfortunately this doesn't work well if there are more transmission lines then one present.
Keith Cress
kcress -
signs everywhere and so it's assumed when a USA call is made all the yokels show up to mark the lack of sewer lines and water pipes and maybe no one shows up to mark the 36" transmission line because, well, DUH, there are already signs. Problem is they don't actually say where the line is other than 'near by'. Then if someone digs by hand carefully and finds the line safely they know where it is and proceed to drill their hole. Unfortunately this doesn't work well if there are more transmission lines then one present.
Keith Cress
kcress -
In general, trenches are much much much much longer than holes. Risk of intersection is thus vastly higher. Obviously. Finding a counterexample doesn't change that.
There would be other factors.
I understand that telephone poles go about 4 feet deep. Who buries pipelines that shallow? Our local NG lateral is (IIRC) about 8-feet deep.
There would be other factors.
I understand that telephone poles go about 4 feet deep. Who buries pipelines that shallow? Our local NG lateral is (IIRC) about 8-feet deep.
VE1BLL…
In the areas I have worked the most (central and southern California), it is very common to see water distribution and natural gas distribution pipelines designed for 3 ft minimum cover (water and gas transmission pipelines are typically deeper). Gravity pipelines, such as sanitary sewers and storm drains, also have this requirement, but in my experience it rarely governs (the need to be below the water and gas mains and the slopes required by hydraulics sends these pipelines deeper). I see this requirement in most of the cities and counties I have worked for, though one city I can think of requires 4 ft minimum cover. I have designed state and federal prison in California and both agencies required 3 ft minimum cover.
Fred
==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill
In the areas I have worked the most (central and southern California), it is very common to see water distribution and natural gas distribution pipelines designed for 3 ft minimum cover (water and gas transmission pipelines are typically deeper). Gravity pipelines, such as sanitary sewers and storm drains, also have this requirement, but in my experience it rarely governs (the need to be below the water and gas mains and the slopes required by hydraulics sends these pipelines deeper). I see this requirement in most of the cities and counties I have worked for, though one city I can think of requires 4 ft minimum cover. I have designed state and federal prison in California and both agencies required 3 ft minimum cover.
Fred
==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill
BridgeSmith
Structural
"I understand that telephone poles go about 4 feet deep."
Maybe in some places, but not here - utility poles never go less than 8 feet here, since the top 5 feet is subject to frost heaving and therefore ignored for lateral stability.
Maybe in some places, but not here - utility poles never go less than 8 feet here, since the top 5 feet is subject to frost heaving and therefore ignored for lateral stability.
In many older parts of cities, the old maps were not very good. Wood pipes don't show up with metal detectors, and clay pipes don't either.
Old is a subjective term (30 years is a common failure time of UG electric, 75 to 100 years is likely the limits for water and sewer).
I would guess a 36" gas line would be made of steel, where the new and smaller lines are now made of plastic.
The location of this event I would doubt would have much frost heave, and might be shallow because of past earth quacks, or other ground movement/water table.
Then again a 36" gas line maybe a transmission line, and the transmission company might not have been given notice to locate. That's likely why they place so many marker posts.
Old is a subjective term (30 years is a common failure time of UG electric, 75 to 100 years is likely the limits for water and sewer).
I would guess a 36" gas line would be made of steel, where the new and smaller lines are now made of plastic.
The location of this event I would doubt would have much frost heave, and might be shallow because of past earth quacks, or other ground movement/water table.
Then again a 36" gas line maybe a transmission line, and the transmission company might not have been given notice to locate. That's likely why they place so many marker posts.
it seems as if two things are being conflated.
The line that was hit in the original post was a 4" distribution line.
The line that was hit by the auger rig boring a hole for the installation of the utility pole was a 36" transmission line with four feet of cover over it. This was the result of multiple breakdowns in communication as explained in detail in the NTSB report here:
I was on a job site once where a 4" distribution line was clipped by a 4" auger being driven by a horizontal directional drilling rig. This became evident when all of the mud in the annulus was blown back suddenly and sprayed all over the rig with no warning, followed by a continuous roar of natural gas. Fortunately (miraculously?) they got the machine turned off before the fuel-air ratio hit the sweet spot for ignition and it just made a lot of noise before the gas company showed up to kill the flow. I was long gone by that point.
There are pros and cons to installing utilities above or below ground. Utility locates are imperfect in either case.
The line that was hit in the original post was a 4" distribution line.
The line that was hit by the auger rig boring a hole for the installation of the utility pole was a 36" transmission line with four feet of cover over it. This was the result of multiple breakdowns in communication as explained in detail in the NTSB report here:
I was on a job site once where a 4" distribution line was clipped by a 4" auger being driven by a horizontal directional drilling rig. This became evident when all of the mud in the annulus was blown back suddenly and sprayed all over the rig with no warning, followed by a continuous roar of natural gas. Fortunately (miraculously?) they got the machine turned off before the fuel-air ratio hit the sweet spot for ignition and it just made a lot of noise before the gas company showed up to kill the flow. I was long gone by that point.
There are pros and cons to installing utilities above or below ground. Utility locates are imperfect in either case.
Spartan…
About 15 years ago I did the site civil design for an ethanol production plant. One thing the owner required of the design-build team (and which I thought was a great idea), was to perform a record survey of the new construction, including N, E, & Z for all underground piping, vaults, etc. before burial. They also surveyed building corners and FF, edges of pavement, etc. The prime contractor told me it added about $30k to a $40M project. The final product from the surveyor was a 3D Autocad drawing of everything underground and at ground. The process team did something similar for the above-ground piping.
Fred
==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill
About 15 years ago I did the site civil design for an ethanol production plant. One thing the owner required of the design-build team (and which I thought was a great idea), was to perform a record survey of the new construction, including N, E, & Z for all underground piping, vaults, etc. before burial. They also surveyed building corners and FF, edges of pavement, etc. The prime contractor told me it added about $30k to a $40M project. The final product from the surveyor was a 3D Autocad drawing of everything underground and at ground. The process team did something similar for the above-ground piping.
Fred
==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill
bacon4life
Electrical
Event without frost heaving, 4 feet would be very shallow for a pole any more than 15 feet tall. Although some folks use the 10% plus 2 feet rule for pole setting, most soil conditions require an even deeper embedment depth.
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