If Two Homes Are Built on This Bernal Heights Property, Will It Explode in a Giant Scorching Fireball?

There’s a design review committee meeting happening tomorrow night, Wednesday, May 28 at 7 pm at the Precita Center.

The topic on the agenda will be that proposal to build two single-family homes at 3516 and 3526 Folsom on the southeast slope of Bernal Hill, on the undeveloped lot just below Bernal Heights Boulevard at Folsom and Chapman. There are questions to consider. Like, how is the new right-of-way going to work, since there’s no road there now, and the slope is so hella steep? And what about drainage, and the garden that’s now on the site, and the existing character of the neighborhood? Also, if homes are built here, will the site explode in a gigantic, scorching, San Bruno-style fireball?

The mortal peril associated with the giant scorching fireball scenario introduces a dramatic new element to the usual Bernal Heights design review fare. The giant scorching fireball scenario has been popularized by some neighbors around the proposed development site, and they have detailed their concerns in a flyer:

Let’s zoom and enhance for better legibility:

Blast radius! Oh my.

But is this true? Is this pipeline the same type that blew up in San Bruno? How likely is it that a giant scorching fireball scenario will ultimately engulf everything inside the red circle?

Remain calm, Citizens of Bernalwood. Let’s walk through this piece by piece.

The gas pipeline that runs through Bernal Heights is called Line 109, and it is definitely serious business. The 2010 San Bruno explosion is fresh in Bay Area memory, but that was Line 132 — a different pipeline altogether. That said, Line 109 also exploded once, in a giant scorching fireball, right here in Bernal Heights, back in 1963.

So there’s that.

Bernalwood reported on the present-day status of Line 109 back in 2011. At the time, we said:

The good news is, our section of Line 109 is relatively new [installed in the early 1980s], and thus hopefully does not have any of the shoddy, 1950s-era welds that were blamed in the San Bruno explosion. Likwise, it seems that an active inspection regimen is in place to validate the line’s integrity.

And so, we concluded:

Given the magnitude of PG&E’s recent mismanagement of its pipeline infrastructure, and the tremendous potential for harm, unwavering diligence will be required by both Bernal Heights residents and our local authorities to ensure the pipeline will remain safe for decades to come.

So, diligence.

That brings us to the present day. Bernalwood has been contacted by a group of neighbors around the proposed development who have been raising alarm about the giant scorching fireball scenario and rallying to oppose construction on the site. We also sent a series of technical questions to PG&E, to get additional information about the status of the pipeline at this location.

We will hear from both sides.

Writing on behalf of the neighbors who oppose the project, Neighbor Maiyah tells Bernalwood:

The site is at Folsom and Chapman, right next to the community garden. There’s a huge gas transmission line right next to the two plots… just like the one in San Bruno. It’s the same line that exploded in 1963 near Alemany and injured 9 firefighters (one also died of a heart attack) and blew up a house. I’m now a part of a small group of concerned Bernal residents who are trying to bring to light the facts of this situation and to inform others of the potential dangers.

I saw the developer (Fabien Lannoye) at the East Slope Design Review Board Meeting in April and he seemed to be not very concerned about the pipeline, not knowing the exact depth of it. He sort of shrugged when he said PG&E had no record of it. Bernal residents had asked him for a comprehensive site plan, the exact location of the pipe, the impact on the nearby community garden, and many more questions and his answer was that he didn’t ever receive the letter in the mail. It made me feel uneasy to say the least.

Just thinking about that huge transmission line with heavy construction equipment digging and moving earth over and around it on one of the steepest grades in San Francisco (35%), makes me cringe.

One of our members recently emailed Robert Bea, Professor Emeritus at the Center for Catastrophic Risk Management at UC Berkeley, who investigated the San Bruno disaster. She asked him if she should be concerned about the pipe line here in Bernal. He replied yes, with the facts that have been gathered so far: (1) the pipeline is old (1980’s) installed in an area with highly variable topography, (2) there are no records on the construction, operation and maintenance of the pipeline, (3) there are no definitive guidelines to determine if the pipeline is ‘safe’ and ‘reliable’, (4) there is apparent confusion about who is responsible (government, industrial – commercial) for the pipeline safety, reliability, and integrity.

This list is identical to the list of concerns that summarized causation of the San Bruno Line 132 gas pipeline disaster.

I live about a block from the proposed construction site, so I’m not too worried, but those of us who live right next to the pipeline are thinking twice about their safety right now.

That’s the argument against building two homes on the lots at 3516 and 3526 Folsom.

To better understand the technical issues, Bernalwood reached out to PG&E with a detailed series of questions related to Line 109 in Bernal Heights and potential construction hazards at the proposed development site. PG&E was very responsive, and we received answers to our questions late last week.

Bernalwood’s questions, and PG&E’s responses, are provided here in their entirety:

1. When was the section of pipeline under the the proposed home site installed? When was it last upgraded?

The line was installed in 1981. PG&E has a comprehensive inspection and monitoring program to ensure the safe operation of this line.

2. How often is this section of 109 inspected? What does the inspection entail? When did the last inspection take place? What were the results of that inspection?

This section of L-109 was successfully strength tested (via a hydrostatic pressure test) at the time of installation. PG&E records show no history of leaks for L-109 in this area.

PG&E has a comprehensive inspection and monitoring program to ensure the safety of its natural gas transmission pipeline system.  PG&E regularly conducts patrols, leak surveys, and cathodic protection (corrosion protection) system inspections for its natural gas pipelines.  Any issues identified as a threat to public safety are addressed immediately.  PG&E also performs integrity assessments of certain gas transmission pipelines in urban and suburban areas.

Patrols:  PG&E patrols its gas transmission pipelines at least quarterly to look for indications of missing pipeline markers, construction activity and other factors that may threaten the pipeline.  L-109 through the [Bernal Heights] neighborhood was last aerially patrolled in May 2014 and no issues were found.

Leak Surveys:  PG&E conducts leak surveys at least annually of its natural gas transmission pipelines.  Leak surveys are generally conducted by a leak surveyor walking above the pipeline with leak detection instruments.  L-109 in San Francisco was last leak surveyed in April 2014 and no leaks were found.

Cathodic Protection System Inspections:  PG&E utilizes an active cathodic protection (CP) system on its gas transmission and steel distribution pipelines to protect them against corrosion.  PG&E inspects its CP systems every two months to ensure they are operating correctly.  The CP systems on L-109 in this area were last inspected in May 2014 and were found to be operating correctly.

Integrity Assessments:  There are three federally-approved methods to complete a transmission pipeline integrity management baseline assessment:  In-Line Inspections (ILI), External Corrosion Direct Assessment (ECDA) and Pressure Testing.  An In-Line Inspection involves a tool (commonly known as a “pig”) being inserted into the pipeline to identify any areas of concern such as potential metal loss (corrosion) or geometric abnormalities (dents) in the pipeline.  An ECDA involves an indirect, above-ground electrical survey to detect coating defects and the level of cathodic protection.  Excavations are performed to do a direct examination of the pipe in areas of concern as required by federal regulations.  Pressure testing is a strength test normally conducted using water, which is also referred to as a hydrostatic test.

PG&E performed an ECDA on L-109 in this area in 2009 and no issues were found.  PG&E plans to perform another ECDA on L-109 in this area in 2015.  This section of L-109 also had an ICDA (Internal Corrosion Direct Assessment) performed in 2012, and no issues were found.

Automated Shut-off Valves: There are two types of automated shut-off valves recognized within the natural gas industry: Remote Controlled Valves (RCV’s), which can be operated remotely from PG&E’s Gas Control Center, and Automatic Shutoff Valves (ASV’s) that will close automatically as a result of rapidly falling pipeline pressures and/or increased flows at the valve location. There is an RCV on L-109 in Daly City that can be used to isolate the section of L-109 that runs through this neighborhood.

3. Is this section of pipeline 109  “the same type that blew up in San Bruno?”

No. Line 109 operates at a much lower pressure and is smaller in diameter, and is of a much more recent vintage.

4. What safety procedures does PG&E put in place when home or street contruction occurs on the site of a major gas pipeline like 109?

Anytime a contractor or resident makes an excavation on franchise or private property, they must call 811 (State Law for Underground Service Alerts [USA]) in advance so we can identify and properly locate our UG facilities.  When our Damage Prevention group gets the USA request and identifies a critical facility like a gas transmission line in the scope of work, they notify the caller that they must contact PG&E for a standby employee.  PG&E must observe a safe excavation around our lines if any digging is within 10’ of it.  We must be present when they dig around this line.  Our standby inspector will instruct and guide the excavating party to avoid damage.  Excavators who violate this Law are subject to fines.

5. Does the steep grade of the Folsom site have any impact on Pipeline 109? Given the grade at the proposed site, are any special provisions or procedures required to ensure the safety of the pipeline during construction?

The grade of the street have no impacts on the operation of the line.  If the cover is not removed or disturbed within 10’ of the line, there are no special precautions needed.

6. Are there any specific technical or safety challenges posed by the proposed home site, and if so, how does PG&E plan to address them?

As long as the structures are built within the property lines similar to the existing [homes on Folsom Street], they will not pose any issues for us patrolling and maintaining that line.  The proposed home sites are not on top of line 109, and are no closer to the line than existing homes in the neighborhood.

Additional Background: In the area outlined in the map [Bernalwood sent PG&E, shown above], PG&E’s natural gas transmission pipeline L-109 runs down Folsom Street and turns east to follow Bernal Heights Blvd.  Line 109 in this area is a 26-inch diameter steel pipeline installed in 1981 and has a maximum allowable operating pressure (MAOP) of 150 pounds per square inch gage (psig), which is 19.8% of the pipe’s specified minimum yield strength (SMYS).  This provides a considerable margin of safety, since it would take a pressure over 750 psig to cause the steel in the pipe to begin to deform.

Whew. Someone should turn that into a TED talk.

Bernalwood’s conclusion from the above is as follows: The handbill that has been posted around Bernal Heights by concerned neighbors contains several errors. Line 109 in Bernal Heights is not the same type of pipeline as Line 132, which exploded in San Bruno. The inspection history provided by PG&E undermines the assertion that “there are no records on the construction, operation and maintenance of the pipeline.” Line 109 has been the subject of a recent and ongoing inspection regimen, and if the developer follows the required safety protocols, the hazards associated with construction on the proposed development site should be routine and manageable.

Here too, rigorous diligence will be required to ensure the project is executed and managed properly. If such diligence is applied, the Citizens of Bernalwood may soon enjoy the company of a few new neighbors on the upper reaches of Folsom Street, without having to endure the hardship and mortal peril associated with a giant scorching fireball emanating from the new home site.

Reasonable minds might reasonably view this matter differently. Either way, see you at the design review meeting, 7pm on Wednesday, May 28 at Precita Center.