PG&E Pipeline Project

Update of Sep 11, 2017

In a meeting with PG&E staff last August, we were told that PG&E does not plan to replace Lines 109 and 132 through Edgewood, nor do they have plans to conduct any additional pressure testing on Lines 109 or 132. Through at least 2024, there should be minimal further maintenance work on these 2 gas pipelines.

Here are the details.

For the past several years, PG&E has been working on developing a Bay-Area Habitat Conservation Plan (HCP). The plan is a comprehensive regional habitat conservation plan for the nine counties surrounding the San Francisco Bay, and is designed to provide long-term conservation and management of sensitive species and the habitats upon which those species depend, while accommodating routine operation and maintenance (O&M) activities and minor construction for PG&E’s gas and electrical distribution facilities.

The 588-page document was submitted to the US Fish & Wildlife Service for assessment and approval. In March 2017, the Service opened a 30-day review period, which it later extended 60 days to June 23, 2017 at the request of several environmental organizations, including Committee for Green Foothills, Citizens Committee to Complete the Refuge, CNPS, and FoE. One of our greatest concerns was that adequate protections to Edgewood’s natural resources would be guaranteed as PG&E performs ongoing maintenance and upgrades on their 2 gas pipelines that run through Edgewood.

As of this date, the USFWS is still reviewing comments that they received on the HCP, so the plan has not been approved yet.

However, PG&E officials kindly offered to meet with representatives from several organizations to discuss the Edgewood gas pipelines specifically, since the HCP was ambiguous about whether replacement of Line 109 would be covered. That meeting took place on Aug 15, 2017 at the Education Center. It was at that meeting that PG&E clarified their plans for operating and maintaining Lines 109 and 132 through Edgewood.

L-109 was installed through Edgewood in 1936; L-132 in 1947. L-109 is 22 inches in diameter, vs. most gas pipelines that are 24 inches, including L-132. Because of its smaller diameter, PG&E is unable to use in-line inspection (ILI) equipment, aka pigs, to test it. However, PG&E did conduct a hydropressure test in October, 2015 and deemed the line safe to operate. PG&E plans to conduct an ILI test of L-132 in the fall of 2017. This test should have no impact on Edgewood’s habitats.

In the future, PG&E needs to verify the integrity of L-109 every seven years, but this can be done by walking along the trace of the pipeline and measuring electrical signals and other indicators. L-132 will continue to be pigged in the future, again without impact on Edgewood’s habitats.

You may be wondering what would happen if a rupture were to occur in one of these lines. Assuming it was not a catastrophic rupture, PG&E would conduct local surgical repairs such as placing a sleeve or replacing a short segment of the line where it had failed. If they felt it was needed, they would reduce the pressure in the line but retain it in service. Then they would analyze the cause of the failure and determine if it was a systematic failure requiring replacement of the line, or if any partial replacement was needed. But all of this would probably kick off a formal permitting process. Emergency environmental permitting (if needed) would include only repairing the failure, and not a broader replacement project.

Line 109 Hydrostatic Pressure Testing

Update of Oct 27, 2015

PG&E has confirmed that the pipeline passed the pressure test and no leaks were detected. PG&E is in the process of putting the line back in service and restoring the area. The restoration will take several years.

Update of Oct 22, 2015

The hydrotest was completed on October 21 without incident. Parks Staff has been monitoring the test, and reported seeing no water on the ground after the pressurization was completed. We are still awaiting details from PG&E.

Original Post of Aug 18, 2015

PG&E is required by the California Public Utilities Commission (CPUC) to perform occasional safety testing on their pipelines. In the case of Line 109, the older of the two lines that run through Edgewood, this testing consists of removing gas from a segment of the line, then filling it with clean hydrant water, pressurizing it to 150% of the normal gas pressure, and assessing its integrity. This procedure is called hydrostatic pressure testing, or simply hydrotesting.

In order to do this test, PG&E needs to access the pipeline by digging at 3 different locations inside the park (and at a 4th location just outside the park in Woodside).

2 of the digs are 6’x6’ “sniff” holes that we expect will create minimal disturbance, but the third dig is a much larger “bell” hole that will cause a greater impact. Referring to the map below, the locations are:

  • First sniff hole. PG&E refers to this location as Location C. It is at the intersection of the Clarkia and Sunset Trails in map quadrant L-11.
  • Second sniff hole. PG&E refers to this location as Location B. It is within the worksite where the Line 132 elbow was replaced 2 years ago, just slightly west of the Edgewood Trail in quadrant H-7.
  • Bell hole. This is also a part of PG&E’s Location B. The digging will occur in quadrant H-7 just northwest of the point where the Ridgeview Trail does a 90 degree right turn. This hole will be one of the 2 holes (the other, PG&E’s Location A, is in Woodside outside of Edgewood) where water will be inserted or drained. So in addition to digging a hole, PG&E needs to have many more vehicles present, including 2 large water-carrying trucks. What makes this dig particularly problematic is finding a way for these trucks to get to the site. There is currently no service road that will work, so PG&E will have to create a new access route running from the Serpentine Trail to the north down to the site.
Existing Pipeline
Hydrotest Project Map
Blue X’s designate sniff hole sites, red circle is the bell hole site

A team consisting of representatives from Committee for Green Foothills, CNPS, MROSD, Parks Department, Creekside Science, FoE, and of course PG&E has met several times since Jun 2015 to discuss specifics about where the holes will be dug (with close attention to minimizing habitat impacts), the plan for restoring the habitat after the construction is completed, pedestrian and truck traffic management, contingencies in case of water leaks, cleaning of equipment and workers’ clothing, and other concerns.

The project started Aug 18, 2015. Signs have been posted throughout the park advising visitors of the project in progress. There will be periodic closures of some trails throughout the course of the project. The project is scheduled to wrap up around mid-Nov 2015 but monitoring to ensure successful habitat restoration will continue for several years.

If you have questions or concerns about this project, you can email them to

Line 109 Replacement

Update of Aug 18, 2015

In the year and a half since our last official meeting with PG&E on this subject on Feb 28, 2014, very little progress has been made. PG&E is in the process of conducting an Environmental Quality Assessment (CEQA) but no lead agency has been identified yet, so this effort is stalled.

Original Post of Mar 2014

In October and November 2013, PG&E replaced an elbow in its Line 132, one of two existing gas pipelines routed through Edgewood, as part of their Pipeline Safety Enhancement Plan (PSEP). Park visitors may have noticed the mowing, digging, and subsequent restoration on two small plots of land near the west kiosk (see Figure 1). PG&E is still in the process of restoring these sites. Friends of Edgewood is working with the California Native Plant Society (CNPS) to oversee the restoration and ensure it is done properly so that no habitat degradation occurs.

Existing Pipeline
Existing Gas Pipelines
with annotations]

The PSEP is PG&E’s multi-year gas transmission system overhaul mandated by the California Public Utilities Commission (CPUC) following the San Bruno incident ( The plan includes laying a new gas pipeline and decommissioning the Edgewood segment of Line 109, which is old (circa 1930s) and substandard (22-inch rather than 24-inch diameter). PG&E has chosen to install the new pipeline through the heart of Edgewood Park.

In order to determine the route of this new pipeline, PG&E evaluated four alternatives (see Figure 2).

Pipeline Routing Analysis
Figure 2. New Pipeline Alternative Routes
[source: PG&E’s Edgewood Preserve Routing Analysis, dated
November 13, 2013; with annotations]
The “Existing Alignment” route parallels the alignment of the existing Line 109. The “Service Corridor” route is a straighter version of the “Existing Alignment” route. The “Substation” route skirts the wetland near the Clarkia Trail, eventually joining Cañada Road and following it to Edgewood Road, then up Edgewood Road to rejoin the existing Line 109. The fourth route, “Ridgeline,” completely avoids Edgewood, traveling through SFPUC Watershed lands on Edgewood’s east boundary, and then under Cañada Road and Edgewood Road.

PG&E has chosen the Service Corridor route and identifies 12 reasons for their decision. These reasons are described on pages 26 and 27 of their routing analysis document. Among them are that this route is the shortest, most direct, will be the simplest to construct, and will be the easiest to operate and maintain. They also claim that this route complies with the Edgewood Master Plan and will cause the least impact to environmental resources, two claims with which we strongly disagree.

A “Pipeline Committee” has been formed, consisting of representatives from Friends of Edgewood, Committee for Green Foothills, the local Santa Clara Valley chapter of the California Native Plant Society, Midpeninsula Regional Open Space District (MROSD), and Creekside Center for Earth Observation.

We have had two formal meetings with PG&E in an effort to convince them to choose the Ridgeline route. Our arguments are:

  • Ridgeline is the only route that completely circumvents Edgewood.
  • The other three routes pass through Edgewood, in violation of the County’s General Plan, the Edgewood Park Master Plan, and the MROSD easement.
  • The other three routes will cause irrecoverable damage to the grasslands inhabited by the Bay checkerspot butterfly, Marin western flax, and White-rayed pentachaeta, all species on the Federal Endangered Species List.

You can find our detailed arguments here.

At our last meeting on Feb. 28, 2014, PG&E told us they would consider our recommendation. Since then, we have had no meaningful feedback. We will, of course, be delighted if PG&E does the “right thing,” but we are currently making plans to fight vigorously if they do not. Without going into details, there are many legal and environmental hurdles that PG&E must overcome, and we believe we can prevent PG&E from disturbing Edgewood.

In the coming weeks, we intend to broaden our support base by engaging more community members. Many of you will recall the valiant fight waged by the Save Edgewood Park Coalition in the early 1990s that resulted in the designation of Edgewood as a Natural Preserve, defeating plans to develop a golf course. We hope you will join us in our battle to Save Edgewood Park again.

In case you are wondering about the impact of digging a new pipeline through Edgewood, imagine an 80-foot wide swath of land stretching approximately 1 mile between the eastern and western boundaries going right across Serpentine grassland, looking like the work site shown in Figure 3.

Pipeline Trench
Figure 3. 80-ft Wide Work Site